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fancy animals, cannot positively tell, until some time after
→the animal has been born, what its
merits or
→form will ultimately turn out. We see this plainly in our own children; we cannot
tell whether
child will be tall or short, or what its precise features will be. The question is not, at what period of life
variation
been caused, but at what period
→it is fully
displayed. The cause may have acted, and I believe
has acted,
→even before the embryo is formed; and the variation may be due to the male and female sexual elements having been affected by the conditions to which either parent, or their ancestors, have been exposed. Nevertheless an effect thus caused at a very early period, even before the formation of the embryo, may appear late in life; as when an hereditary disease, which appears in old age alone, has been communicated to the offspring from the reproductive element of one parent. Or again, as when the horns of cross-bred cattle have been affected by the shape of the horns of either parent.
→For the welfare of
a very young animal, as long as it remains in its
or in the egg, or as long as it is nourished and protected by its parent,
→be quite unimportant whether most
of its characters are
acquired a little earlier or later in life. It would not signify, for instance, to a bird which obtained its food
by having a
whether or not
→it assumed
a beak of this
as long as it was fed by its parents. Hence, I conclude, that it is quite possible, that each of the many successive modifications, by which each species has acquired its present structure, may have supervened at a not very early period of life; and some direct evidence from our domestic animals supports this view. But in other cases it is quite possible that each successive modification, or
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