Chap. Y. 
LAWS OF VARIATION. 
159 
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 repre¬ 
senting the normal structure of another race, the fan- 
tail. 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 vege¬ 
table kingdom we have a case of analogous variation, in 
the enlarged stems, or roots as commonly called, of the 
Swedish turnip and Euta 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 
