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Vries, Hugo de, 1848-1935

"Species and Varieties, Their Origin by Mutation"

This question is of paramount importance in the consideration of
the offspring of the hybrids. But before taking it up it is as well to
learn the real signification of recessiveness in the hybrids themselves.
Recessive characters are shown by those rare cases, in which hybrids
revert to the varietal parent in the vegetative way. In other words by
bud-variations or sports, analogous to the splitting of Adam's laburnum
into its parents, by means of bud-variation already described. But here
the wide range of differentiating characters of the parents of this most
curious hybrid fail. The illustrative examples are extremely simple, and
are limited to the active and inactive condition of only one quality.
An instance is given by the long-leaved veronica (_Veronica
longifolia_), which has bluish flowers in long spikes. The hybrid
between [285] this species and its white variety has a blue corolla. But
occasionally it produces some purely white flowers, showing its power of
separating the parental heritages, combined in its internal structures.
This reversion is not common, but in thousands of flowering spikes one
may expect to find at least one of them. Sometimes it is a whole stem
springing from the underground system and bearing only white flowers on
all its spikes. In other instances it is only a side branch which
reverts and forms white flowers on a stem, the other spikes of which
remain bluish.


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