Reversion means the falling
back or returning to another type, and the word itself expresses the
idea that this latter type is the form from which the variety has
arisen.
Some instances of atavism of this kind are well known, as they are often
repeated by individuals that are multiplied by buds or by grafting.
Before looking attentively into the different features of the many cases
of rare reversions it will be advisable to quote a few examples.
The flowering-currant of the Pacific Coast or North American scarlet
ribes (_Ribes sanguineum_), a very popular ornamental shrub, will serve
as a good example. It is prized because of its brilliant red racemes of
flowers which blossom early in the spring, before the appearance of the
leaves. From this species a white form has arisen, which is an old and
widely cultivated one, but not so highly prized because of its pale
flowers. These are not of a pure white, but have retained a faint
reddish hue. The young twigs and the stalks of the [167] leaves afford
an instance of correlated variability since in the species the red color
shows itself clearly mixed with the green, while in the variety this
tinge is wholly wanting.
Occasionally this white-flowered currant reverts back to the original
red type and the reversion takes place in the bud.
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