Florists may learn from the four cases which have been fully described,
that they have the power of fixing each fleeting variety of colour, if
they will fertilise the flowers of the desired kind with their own
pollen for half-a-dozen generations, and grow the seedlings under the
same conditions. But a cross with any other individual of the same
variety must be carefully prevented, as each has its own peculiar
constitution. After a dozen generations of self-fertilisation, it is
probable that the new variety would remain constant even if grown under
somewhat different conditions; and there would no longer be any
necessity to guard against intercrosses between the individuals of the
same variety.
With respect to mankind, my son George has endeavoured to discover by a
statistical investigation whether the marriages of first cousins are at
all injurious, although this is a degree of relationship which would not
be objected to in our domestic animals; and he has come to the
conclusion from his own researches and those of Dr. Mitchell that the
evidence as to any evil thus caused is conflicting, but on the whole
points to its being very small. From the facts given in this volume we
may infer that with mankind the marriages of nearly related persons,
some of whose parents and ancestors had lived under very different
conditions, would be much less injurious than that of persons who had
always lived in the same place and followed the same habits of life.
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