Such buds can be propagated by grafting, etc., and sometimes by
seed. These "sports" are extremely rare under nature, but far from
rare under cultivation; and in this case we see that the treatment of
the parent has affected a bud or offset, and not the ovules or pollen.
But it is the opinion of most physiologists that there is no essential
difference between a bud and an ovule in their earliest stages of
formation; so that, in fact, "sports" support my view, that
variability may be largely attributed to the ovules or pollen, or to
both, having been affected by the treatment of the parent prior to the
act of conception. These cases anyhow show that variation is not
necessarily connected, as some authors have supposed, with the act of
generation.
Seedlings from the same fruit, and the young of the same litter,
sometimes differ considerably from each other, though both the young
and the parents, as Muller has remarked, have apparently been exposed
to exactly the same conditions of life; and this shows how unimportant
the direct effects of the conditions of life are in comparison with
the laws of reproduction, and of growth, and of inheritance; for had
the action of the conditions been direct, if any of the young had
varied, all would probably have varied in the same manner. To judge
how much, in the case of any variation, we should attribute to the
direct action of heat, moisture, light, food, etc., is most difficult:
my impression is, that with animals such agencies have produced very
little direct effect, though apparently more in the case of plants.
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