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
The next evidence is supplied by an exceptionally complete record of
a most valuable experiment made by Laxton[104]. The whole story is
replete with interest, and as it not only carries us on somewhat beyond
the point reached by Mendel, but furnishes an excellent illustration of
how his principles may be applied, I give the whole account in Laxton’s
words, only altering the paragraphing for clearness, and adding a
commentary. The paper appears in _Jour. Hort. Soc._ N.S. III. 1872,
p. 10, and very slightly abbreviated in _Jour. of Hort._ XVIII. 1870,
p. 86. Some points in the same article do not specially relate to this
section, but for simplicity I treat the whole together.
[104] It will be well known to all practical horticulturalists that Laxton,
originally of Stamford, made and brought out a large number of the best
known modern peas. The firm is now in Bedford.
It is not too much to say that two years ago the whole of this story
would have been a maze of bewildering confusion. There are still some
points in it that we cannot fully comprehend, for the case is one of
far more than ordinary complexity, but the general outlines are now
clear. In attempting to elucidate the phenomena it will be remembered
that there are no statistics (those given being inapplicable), and the
several offspring are only imperfectly referred to the several classes
of seeds. This being so, our rationale cannot hope to be complete.
Laxton states that as the seeds of peas are liable to change colour
with keeping, for this and other reasons he sent to the Society a part
of the seeds resulting from his experiment before it was brought to a
conclusion.
“The seeds exhibited were derived from a single experiment. Amongst
these seeds will be observed some of several remarkable colours,
including black, violet, purple-streaked and spotted, maple, grey,
greenish, white, and almost every intermediate tint, the varied
colours being apparently produced on the outer coat or envelope of
the cotyledons only.
The peas were selected for their colours, &c., from the third year’s
sowing in 1869 of the produce of a cross in 1866 of the early round
white-seeded and white-flowered garden variety “Ringleader,” which
is about 2-1/2 ft. in height, fertilised by the pollen of the common
purple-flowered “maple” pea, which is taller than “Ringleader,” and
has slightly indented seeds. I effected impregnation by removing
the anthers of the seed-bearer, and applying the pollen at an early
stage. This cross produced a pod containing five round white peas,
exactly like the ordinary “Ringleader” seeds[105].
[105] A round white ♀ × grey ♂ giving the usual result, round,
“white” (yellow) seeds.
Public-domain text, read in full here on John Shaqi.
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