This shows us how little change is produced by mere
cultivation, or even by variety of soil and climate, if there is no
_selection_ to preserve and accumulate the small variations that are
continually occurring. When, however, a great amount of modification has
been effected in one country, change to another country produces a
decided effect. Thus it has been found that some of the numerous
varieties of maize produced and cultivated in the United States change
considerably, not only in their size and colour, but even in the shape
of the seed when grown for a few successive years in Germany.[31] In all
our cultivated fruit trees the fruits vary immensely 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.
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