So that the
crossed plants, far from beating the self-fertilised, were completely
beaten by them.
There can be no doubt that the result would have been widely different,
if any two varieties out of the numberless ones which exist had been
crossed. Notwithstanding that both had been self-fertilised for many
previous generations, each would almost certainly have possessed its own
peculiar constitution; and this degree of differentiation would have
been sufficient to make a cross highly beneficial. I have spoken thus
confidently of the benefit which would have been derived from crossing
any two varieties of the pea from the following facts: Andrew Knight in
speaking of the results of crossing reciprocally very tall and short
varieties, says, "I had in this experiment a striking instance of the
stimulative effects of crossing the breeds; for the smallest variety,
whose height rarely exceeded 2 feet, was increased to 6 feet; whilst the
height of the large and luxuriant kind was very little diminished."
(5/15. 'Philosophical Transactions' 1799 page 200.) Recently Mr. Laxton
has made numerous crosses, and everyone had been astonished at the
vigour and luxuriance of the new varieties which he has thus raised and
afterwards fixed by selection. He gave me seed-peas produced from
crosses between four distinct kinds; and the plants thus raised were
extraordinarily vigorous, being in each case from 1 to 2 or even 3 feet
taller than the parent-forms, which were raised at the same time close
alongside.
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