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
This plant is monoecious, and was selected for trial on this account, no
other such plant having been experimented on. (6/8. Hildebrand remarks
that this species seems at first sight adapted to be fertilised by
pollen from the same plant, owing to the male flowers standing above the
female flowers; but practically it must generally be fertilised by
pollen from another plant, as the male flowers usually shed their pollen
before the female flowers are mature: ‘Monatsbericht der K. Akad.’
Berlin October 1872 page 743.) It is also anemophilous, or is fertilised
by the wind; and of such plants only the common beet had been tried.
Some plants were raised in the greenhouse, and were crossed with pollen
taken from a distinct plant; and a single plant, growing quite
separately in a different part of the house, was allowed to fertilise
itself spontaneously. The seeds thus obtained were placed on damp sand,
and as they germinated in pairs of equal age were planted on the
opposite sides of four very large pots; nevertheless they were
considerably crowded. The pots were kept in the hothouse. The plants
were first measured to the tips of their leaves when only between 1 and
2 feet in height, as shown in Table 6/97.
TABLE 6/97. Zea mays.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 23 4/8 : 17 3/8.
Pot 1 : 12 : 20 3/8.
Pot 1 : 21 : 20.
Pot 2 : 22 : 20.
Pot 2 : 19 1/8 : 18 3/8.
Pot 2 : 21 4/8 : 18 5/8.
Pot 3 : 22 1/8 : 18 5/8.
Pot 3 : 20 3/8 : 15 2/8.
Pot 3 : 18 2/8 : 16 4/8.
Pot 3 : 21 5/8 : 18.
Pot 3 : 23 2/8 : 16 2/8.
Pot 4 : 21 : 18.
Pot 4 : 22 1/8 : 12 6/8.
Pot 4 : 23 : 15 4/8.
Pot 4 : 12 : 18.
Total : 302.88 : 263.63.
The fifteen crossed plants here average 20.19, and the fifteen
self-fertilised plants 17.57 inches in height; or as 100 to 87. Mr.
Galton made a graphical representation, in accordance with the method
described in the introductory chapter, of the above measurements, and
adds the words “very good” to the curves thus formed.
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