CHAP. V.] ANALOGOUS VARIATIONS. 117 



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 com- 

 monly 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 basis 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 liable to appear in the crossed offspring of two distinct 

 and differently coloured breeds ; and in this case there is nothing 

 in the external conditions of life to cause the reappearance of the 

 slaty-blue, with the several marks, beyond the influence of the 

 mere act of crossing on the laws of inheritance. 



No doubt it is a very surprising fact that characters should 

 reappear after having been lost for many, probably for hundreds 

 of generations. But when a breed has been crossed only once 



