a few almost wild seedlings often
reappear through reversion. On comparing the choicest varieties with
the nearest allied wild forms, besides the difference in the size,
outline, and colour of the flowers, the leaves are seen sometimes to
differ in shape, as does the calyx occasionally in the length and
breadth of the sepals. The differences in the form of the nectary more
especially deserve notice; because characters derived from this organ
have been much used in the discrimination of most of the species of
Viola. In a large number of flowers compared in 1842 I found that in
the greater number the nectary was straight; in others the extremity
was a little turned upwards, or downwards, or inwards, so as to be
completely hooked; in others, instead of being hooked, it was first
turned rectangularly downwards, and then backwards and upwards; in
others the extremity was considerably enlarged; and lastly, in some the
basal part was depressed, becoming, as usual, laterally compressed
towards the extremity. In a large number of flowers, on the other hand,
examined by me in 1856 from a nursery-garden in a different part of
England, the nectary hardly varied at all. Now M. Gay says that in
certain districts, especially in Auvergne, the nectary of the wild _V.
grandiflora_ varies in the manner just described. Must we conclude from
this that the cultivated varieties first mentioned were all descended
from _V. grandiflora_, and that the second lot, though having the same
general appearance, were descended from _V. tricolor_, of which the
nectary, according to M. Gay, is subject to little variation? Or is it
not more probable that both these wild forms would be found under other
conditions to vary in the same manner and degree, thus showing that
they ought not to be ranked as specifically distinct?

The _Dahlia_ has been referred to by almost every author who has
written on the variation of plants, because it is believed that all the
varieties are descended from a single species, and because all have
arisen since 1802 in France, and since 1804 in England.[802] Mr. Sabine
remarks that "it seems as if some period of cultivation had been
required before the fixed qualities of the native plant gave way and
began to sport into those changes which now so delight us."[803] The
flowers have been greatly modi