Mendel's principles of heredity: A defenceMendel, Gregor
Science
Mendel's principles of heredity: A defence
Mendel, Gregor
Heredity; Hybridization; Mendel's law; Weldon, Walter Frank Raphael. Mendel's laws of alternative inheritance in peas
In the second generation blue wrinkled give only blue wrinkled, and
blue round give blue wrinkled and round, in accordance with general
experience. But we are told that white round give _only_ white round.
This would be true of some white rounds, but not, according to
general experience, of all. Lastly we are told _white wrinkled give
all four classes_. If we had not been just told by Laxton that the
first cross showed dominance of white round, and that blue wrinkled
and blue round give the Mendelian result, I should hesitate in face
of this positive statement, but as it is inconsistent with the rest
of the story I think it is unquestionably an error of statement. The
context, and the argument based on the maple crosses show clearly
also what was in Laxton’s mind. He plainly expected the characters
of the original pure varieties to separate out according to their
original combinations, and this expectation confused his memory and
general impressions. This, at least, until any such result is got
by a fresh observer, using strict methods, is the only acceptable
account.
Of the same nature is the statement given by the late Mr Masters
to Darwin (_Animals and Plants_, I. p. 318) that blue round, white
round, blue wrinkled, and white wrinkled, all reproduced all four
sorts during successive years. Seeing that one sort would give
all four, and two would give two kinds, without special counting
such an impression might easily be produced. There are the further
difficulties due to seed-coat colour, and the fact that the
distinction between round and wrinkled may need some discrimination.
The sorts are not named, and the case cannot be further tested.
[127] See later.
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