Chap. V.] CHARACTERS VARIABLE. 125 



less completely, according to the lapse of time, overmastered the 

 tendency to reversion and to further variability, — to sexual selection 

 being less rigid than ordinary selection, — and to variations in the 

 same parts having been accumulated by natural and sexual selection, 

 and having been thus adapted for secondary sexual, and for ordinary 

 purposes. 



Distinct Species present analogous Variations, so that a Variety 

 of one Species often assumes a Character proper to 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 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 tbe 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 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. 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 occa- 

 sional 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- 



