e maintains therefore, that the laws
of multiplication and variation cannot furnish the right kinds of
materials at the right times for natural selection to work on. I
believe, on the contrary, that it can be logically _proved_ from the six
axiomatic laws before laid down, that such materials would be furnished;
but I prefer to show there are abundance of _facts_ which demonstrate
that they are furnished.

The experience of all cultivators of plants and breeders of animals
shows, that when a sufficient number of individuals are examined,
variations of any required kind can always be met with. On this depends
the possibility of obtaining breeds, races, and fixed varieties of
animals and plants; and it is found, that any one form of variation may
be accumulated by selection, without materially affecting the other
characters of the species; each _seems_ to vary in the one required
direction only. For example, in turnips, radishes, potatoes, and
carrots, the root or tuber varies in size, colour, form, and flavour,
while the foliage and flowers seem to remain almost stationary; in the
cabbage and lettuce, on the contrary, the foliage can be modified into
various forms and modes of growth, the root, flower, and fruit remaining
little altered; in the cauliflower and brocoli the flower heads vary; in
the garden pea the pod only changes. We get innumerable forms of fruit
in the apple and pear, while the leaves and flowers remain
undistinguishable; the same occurs in the gooseberry and garden currant.
Directly however, (in the very same genus) we want the flower to vary in
the Ribes sanguineum, it does so, although mere cultivation for hundreds
of years has not produced marked differences in the flowers of Ribes
grossularia. When fashion demands any particular change in the form or
size, or colour of a flower, sufficient variation always occurs in the
right direction, as is shown by our roses, auriculas, and geraniums;
when, as recently, ornamental leaves come into fashion sufficient
variation is found to meet the demand, and we have zoned pelargoniums,
and variegated ivy, and it is discovered that a host of our commonest
shrubs and herbaceous plants have taken to vary in this direction just
when we want them to do so! This rapid variation is not confined to old
and well-known plants subjected for a long series of generations to
cultivation, but the Sikim Rhododendrons, the Fuchsias, and Calceolarias
from the Andes, and the Pelar