Chap. V.] ANALOGOUS VARIATIONS. 195 



severalraces 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 varia- 

 tion, 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 cultiva- 

 tion 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 Nauclin 

 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 varia- 

 tion appearing in the several breeds. We may, I 

 think, confidently come to this conclusion, because, as 



