CHARACTERS OF AN EARLY PROGENITOR.

These propositions will be most readily understood by looking to our
domestic races. The most distinct breeds of the pigeon, in countries
widely apart, present sub-varieties with reversed feathers on the
head, and with 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 as commonly called roots,
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. Many
similar cases of analogous variation have been observed by Naudin in the
great gourd family, and by various authors in our cereals. Similar
cases occurring with insects under natural conditions have lately been
discussed with much ability by Mr. Walsh, who has grouped them under his
law of equable variability.

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, white loins, 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 eminent