23 DOMESTIC PIGEON'S. 



have, besides the two black bars, the wings checkered with 

 black. These several marks do not occur together in any 

 other species of the whole family. Now, in every one of the 

 domestic breeds, taking thoroughly well-bred birds, all the 

 above marks, even to the white edging of the outer tail- 

 feathers, sometimes concur perfectly developed. More- 

 over, when birds belonging to two or more distinct breeds 

 are crossed, none of which are blue or have any of the 

 above-specified marks, the mongrel offspring are very 

 apt suddenly to acquire these characters. To give 

 one instance out of several which I have observed : 

 I crossed some white fantails, which breed very 

 true, with some black barbs— and it so happens that 

 blue varieties of barbs are so rare that I never heard of an 

 instance in England; and the mongrels were black, brown 

 and mottled. I also crossed a barb with a spot, which is a 

 white bird with a red tail and red spot on the forehead, 

 and which notoriously breeds very true; the mongrels were 

 dusky and mottled. I then crossed one of the mongrel 

 barb-fantails with a mongrel barb-spot, and they produced 

 a bird of as beautiful a blue color, with the white loins, 

 double black wing-bar, and barred and white-edged tail- 

 feathers, as any wild rock-pigeon ! We can understand 

 these facts, on the well-known principle of reversion to 

 ancestral characters, if all the domestic breeds are de- 

 scended from the rock-pigeon. But, if we deny this, we 

 must make one of the two following highly improbable 

 suppositions. Either, first, that all the several imagined 

 aboriginal stocks were colored and marked like the rock- 

 pigeon, although no^ other existing species is thus colored 

 and marked, so that in each separate breed there might be 

 a tendency to revert to the very same colors and markings. 

 Or, secondly, that each breed, even the purest, has within 

 a dozen, or at most within a score, of generations, been 

 crossed by the rock-pigeon: I say within a dozen or twenty 

 generations, for no instance is known of crossed descend- 

 ants reverting to an ancestor of foreign blood, removed by 

 a greater number of generations. In a breed which has 

 been crossed only once the tendency to revert to any 

 character derived from such a cross will naturally become 

 less and less, as in each succeeding generation there will be 

 less of the foreign blood; but when there has been no cross, 



