With P. auricula and farinosa the stamens resemble
those of the short-styled form in length, but those of the long-styled in the
size of their pollen-grains; the pistil also resembles that of the long-styled,
so that although the stamens and pistil are of nearly equal length, and
consequently pollen is spontaneously deposited on the stigma, yet the flowers
are not legitimately fertilised and yield only a very moderate supply of seed.
We thus see, firstly, that equal-styled varieties have originated in various
ways, and, secondly, that the combination of the two forms in the same flower
differs in completeness. With P. elatior some of the flowers on the same plant
have become equal-styled, instead of all of them as in the other species.
Mr. Scott has suggested that the equal-styled varieties arise through reversion
to the former homostyled condition of the genus. This view is supported by the
remarkable fidelity with which the equal-styled variation is transmitted after
it has once appeared. I have shown in Chapter 13 of my 'Variation of Animals and
Plants under Domestication,' that any cause which disturbs the constitution
tends to induce reversion, and it is chiefly the cultivated species of Primula
which become equal-styled. Illegitimate fertilisation, which is an abnormal
process, is likewise an exciting cause; and with illegitimately descended long-
styled plants of P.
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