LAWS OF VARIATION 221 



■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 com- 

 munity 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 varia- 

 tion 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 ail 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 exter- 

 nally edged near their basis with white. As all these 

 marks are characteristic of the parent rock-pigeon, I pre- 

 sume that no one will doubt that this is a case of rever- 

 sion, and not of a new yet analogous variation appearing 

 in the several breeds. We may, I think, confidently come 

 to tnis conclusion, because, as we have seen, these colored 

 marks are eminently liable to appear in the crossed off- 

 spring of two distinct and differently colored 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 



