in shape, size,
colour, flavour, time of ripening, and other qualities, while the leaves
and flowers usually differ so little that they are hardly
distinguishable except to a very close observer.

_Variations of Apples and of Melons._

The most remarkable varieties are afforded by the apple and the melon,
and some account of these will be given as illustrating the effects of
slight variations accumulated by selection. All our apples are known to
have descended from the common crab of our hedges (Pyrus malus), and
from this at least a thousand distinct varieties have been produced.
These differ greatly in the size and form of the fruit, in its colour,
and in the texture of the skin. They further differ in the time of
ripening, in their flavour, and in their keeping properties; but apple
trees also differ in many other ways. The foliage of the different
varieties can often be distinguished by peculiarities of form and
colour, and it varies considerably in the time of its appearance; in
some hardly a leaf appears till the tree is in full bloom, while others
produce their leaves so early as almost to hide the flowers. The flowers
differ in size and colour, and in one case in structure also, that of
the St. Valery apple having a double calyx with ten divisions, and
fourteen styles with oblique stigmas, but without stamens or corolla.
The flowers, therefore, have to be fertilised with the pollen from other
varieties in order to produce fruit. The pips or seeds differ also in
shape, size, and colour; some varieties are liable to canker more than
others, while the Winter Majetin and one or two others have the strange
constitutional peculiarity of never being attacked by the mealy bug even
when all the other trees in the same orchard are infested with it.

All the cucumbers and gourds vary immensely, but the melon (Cucumis
melo) exceeds them all. A French botanist, M. Naudin, devoted six years
to their study. He found that previous botanists had described thirty
distinct species, as they thought, which were really only varieties of
melons. They differ chiefly in their fruits, but also very much in
foliage and mode of growth. Some melons are only as large as small
plums, others weigh as much as sixty-six pounds. One variety has a
scarlet fruit. Another is not more than an inch in diameter, but
sometimes more than a yard in length, twisting about in all directions
like a serpent. Some melons are exactly like cucumbers; and an