* * * * *
Most of the facts hitherto given have served to illustrate the force of
inheritance, but we must now consider cases, grouped as well as the subject
allows into classes, showing how feeble, capricious, or deficient the power
of inheritance sometimes is. When a new peculiarity first appears, we can
never predict whether it will be inherited. If both parents from their
birth present {18} the same peculiarity, the probability is strong that it
will be transmitted to at least some of their offspring. We have seen that
variegation is transmitted much more feebly by seed from a branch which had
become variegated through bud-variation, than from plants which were
variegated as seedlings. With most plants the power of transmission
notoriously depends on some innate capacity in the individual: thus
Vilmorin[43] raised from a peculiarly coloured balsam some seedlings, which
all resembled their parent; but of these seedlings some failed to transmit
the new character, whilst others transmitted it to all their descendants
during several successive generations. So again with a variety of the rose,
two plants alone out of six were found by Vilmorin to be capable of
transmitting the desired character.
The weeping or pendulous growth of trees is strongly inherited in some
cases, and, without any assignable reason, feebly in other cases. I
have selected this character as an instance of capricious inheritance,
because it is certainly not proper to the parent-species, and because,
both sexes being borne on the same tree, both tend to transmit the same
character. Even supposing that there may have been in some instances
crossing with adjoining trees of the same species, it is not probable
that all the seedlings would have been thus affected. At Moccas Court
there is a famous weeping oak; many of its branches "are 30 feet long,
and no thicker in any part of this length than a common rope:" this
tree transmits its weeping character, in a greater or less degree, to
all its seedlings; some of the young oaks being so flexible that they
have to be supported by props; others not showing the weeping tendency
till about twenty years old.[44] Mr. Rivers fertilized, as he informs
me, the flowers of a new Belgian weeping thorn (_Crataegus oxyacantha_)
with pollen from a crimson not-weeping variety, and three young trees,
"now six or seven years old, show a decided tendency to be pendulous,
but as yet are not so much so as the mother-plant." According to Mr.
MacNab,[45] seedlings from a magnificent weeping birch (_Betula alba_),
in the Botanic Garden at Edinburgh, grew for the first ten or fifteen
years upright, but then all became weepers like their parent. A peach
with pendulous branches, like those of the weeping willow, has been
found capable of propagation by seed.[46] Lastly, a weeping and almost
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