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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

As it was scarcely possible to measure their heights, the
finest plant on each side of each pot was cut down close to the ground
and weighed. In Table 4/30 we have the result.
The six finest crossed plants average 108.16 ounces, whilst the six
finest self-fertilised plants average only 23.7 ounces, or as 100 to 22.
This difference shows in the clearest manner the enormous benefit which
these plants derived from a cross with another plant belonging to the
same sub-variety, but to a fresh stock, and grown during at least the
three previous generations under somewhat different conditions.
THE OFFSPRING FROM A CUT-LEAVED, CURLED, AND VARIEGATED WHITE-GREEN
CABBAGE CROSSED WITH A CUT-LEAVED, CURLED, AND VARIEGATED CRIMSON-GREEN
CABBAGE, COMPARED WITH THE SELF-FERTILISED OFFSPRING FROM THE TWO
VARIETIES.
These trials were made, not for the sake of comparing the growth of the
crossed and self-fertilised seedlings, but because I had seen it stated
that these varieties would not naturally intercross when growing
uncovered and near one another. This statement proved quite erroneous;
but the white-green variety was in some degree sterile in my garden,
producing little pollen and few seeds. It was therefore no wonder that
seedlings raised from the self-fertilised flowers of this variety were
greatly exceeded in height by seedlings from a cross between it and the
more vigorous crimson-green variety; and nothing more need be said about
this experiment.


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