Ipomoea purpurea.
My attention was first drawn to the present subject by observing that
the flowers on all the plants of the seventh self-fertilised generation
were of a uniform, remarkably rich, dark purple tint. The many plants
which were raised during the three succeeding generations, up to the
last or tenth, all produced flowers coloured in the same manner. They
were absolutely uniform in tint, like those of a constant species living
in a state of nature; and the self-fertilised plants might have been
distinguished with certainty, as my gardener remarked, without the aid
of labels, from the intercrossed plants of the later generations. These,
however, had more uniformly coloured flowers than those which were first
raised from the purchased seeds. This dark purple variety did not
appear, as far as my gardener and myself could recollect, before the
fifth or sixth self-fertilised generation. However this may have been,
it became, through continued self-fertilisation and the cultivation of
the plants under uniform conditions, perfectly constant, to the
exclusion of every other variety.
Dianthus caryophyllus.
The self-fertilised plants of the third generation all bore flowers of
exactly the same pale rose-colour; and in this respect they differed
quite remarkably from the plants growing in a large bed close by and
raised from seeds purchased from the same nursery garden.
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