otato
varying in the same manner,--all the fruit on a purple plum-tree suddenly
becoming yellow,--all the fruit on a double-flowered almond suddenly
becoming peach-like,--all the buds on grafted trees being in some very
slight degree affected by the stock on which they have been worked,--all
the flowers on a transplanted heartsease changing for a time in colour,
size, and shape,--we are led through such facts to look at every case of
bud-variation as the direct result of the particular conditions of life to
which the plant has been exposed. But if we turn to the other end of the
series, namely, to such cases as that of a peach-tree which, after having
been cultivated by tens of thousands during many years in many countries,
and after having annually produced thousands of buds, all of which have
apparently been exposed to precisely the same conditions, yet at last
suddenly produces a single bud with its whole character greatly
transformed, we are driven to an opposite {409} conclusion. In such cases
as the latter it would appear that the transformation stands in no _direct_
relation to the conditions of life.

We have seen that varieties produced from seeds and from buds resemble each
other so closely in general appearance, that they cannot possibly be
distinguished. Just as certain species and groups of species, when
propagated by seed, are more variable than other species or genera, so it
is in the case of certain bud-varieties. Thus the Queen of England
Chrysanthemum has produced by this latter process no less than six, and
Rollisson's Unique Pelargonium four distinct varieties; moss-roses have
also produced several other moss-roses. The Rosaceae have varied by buds
more than any other group of plants; but this may be in large part due to
so many members having been long cultivated; but within this one group, the
peach has often varied by buds, whilst the apple and pear, both grafted
trees extensively cultivated, have afforded, as far as I can ascertain,
extremely few instances of bud-variation.

The law of analogous variation holds good with varieties produced by buds,
as with those produced from seed: more than one kind of rose has sported
into a moss-rose; more than one kind of camellia has assumed an hexagonal
form; and at least seven or eight varieties of the peach have produced
nectarines.

The laws of inheritance seem to be nearly the same with seminal and
bud-varieties. We know how commonly reversion comes i