n the same parts having been accumulated
by natural and sexual selection, and thus adapted for secondary sexual,
and for ordinary specific purposes.

DISTINCT SPECIES PRESENT ANALOGOUS VARIATIONS; AND A VARIETY OF ONE
SPECIES OFTEN ASSUMES SOME OF THE CHARACTERS OF AN ALLIED SPECIES, OR
REVERTS TO SOME OF THE CHARACTERS OF AN EARLY PROGENITOR.

These propositions will be most readily understood by looking to our
domestic races. The most distinct breeds of pigeons, in countries most
widely apart, present sub-varieties with reversed feathers on the head
and feathers on the feet,--characters not possessed by the aboriginal
rock-pigeon; these then are analogous variations in two or more distinct
races. The frequent presence of fourteen or even sixteen tail-feathers
in the pouter, may be considered as a variation representing the normal
structure of another race, the fantail. I presume that no one will doubt
that all such analogous variations are due to the several races of the
pigeon having inherited from a common parent the same constitution and
tendency to variation, when acted on by similar unknown influences.
In the vegetable kingdom we have a case of analogous variation, in the
enlarged stems, or roots as commonly called, of the Swedish turnip and
Ruta baga, plants which several botanists rank as varieties produced by
cultivation from a common parent: if this be not so, the case will then
be one of analogous variation in two so-called distinct species; and to
these a third may be added, namely, the common turnip. According to
the ordinary view of each species having been independently created, we
should have to attribute this similarity in the enlarged stems of these
three plants, not to the vera causa of community of descent, and a
consequent tendency to vary in a like manner, but to three separate yet
closely related acts of creation.

With pigeons, however, we have another case, namely, the occasional
appearance in all the breeds, of slaty-blue birds with two black bars
on the wings, a white rump, a bar at the end of the tail, with the outer
feathers externally edged near their bases with white. As all these
marks are characteristic of the parent rock-pigeon, I presume that no
one will doubt that this is a case of reversion, and not of a new yet
analogous variation appearing in the several breeds. We may I think
confidently come to this conclusion, because, as we have seen, these
coloured marks are eminently liabl