80 PIGEONS. 



although no other existing species is thus coloured and marked, so that in each 

 separate breed there might be a tendency to revert to the very same colours 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 Eock Pigeon. I say 

 within a dozen or twenty generations, for we know of no fact countenancing the 

 belief that the child ever reverts to some one ancestor removed by a greater 

 number of generations. In a breed which has been crossed only once with some 

 distinct breed, the tendency to reversion to any character derived from such 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 with a distinct breed, 

 and there is a tendency in both parents to revert to a character which has been 

 lost during some former generation, this tendency, for all that we can see to the 

 contrary, may be transmitted undiminished for an indefinite number of genera- 

 tions. These two distinct cases are often confounded in treatises on inheritance. 



"Lastly, the hybrids or mongrels from between all the domestic breeds of 

 pigeons are perfectly fertile. I can state this from my own observations, purposely 

 made on the most distinct breeds. Now, it is difficult, perhaps impossible, to 

 bring forward one case of the hybrid offspring of two animals clearly distinct, 

 being themselves perfectly fertile. Some authors believe that long-continued 

 domestication eliminates this strong tendency to sterility : from the history of the 

 dog, I think there is some probability in this hypothesis, if applied to species 

 closely related together, though it is unsupported by a single experiment. But to 

 extend the hypothesis so far as to suppose that species aboriginally as distinct 

 as Carriers, Tumblers, Pouters, and Fantails now are, should yield offspring 

 perfectly fertile, inter se, seems to me rash in the extreme. 



" From these several reasons, namely, the improbability of man having 

 formerly got seven or eight supposed species of pigeons to breed freely under 

 domestication ; these supposed species being quite unknown in a wild state, and 

 their becoming nowhere feral ; these species having very abnormal characters in 

 certain respects, as compared with all other Columbidce, though so like in most 

 other respects to the Rock Pigeon ; the blue colour and various marks occasionally 

 appearing in all the breeds, both when kept pure and when crossed ; the mongrel 

 offspring being perfectly fertile : from these several reasons, taken together, I can 

 feel no doubt that all our domestic breeds have descended from the Columba livia, 

 with its geographical sub-species. 



" In favour of this view, I mav add, firstly, that C. livia, or the Piock 

 Pigeon, has been found capable of domestication in Europe and in India, and 

 that it agrees in habits and in a great number of points of structure with all the 

 domestic breeds. Secondly, although an English Carrier, or Short-faced Tumbler, 

 differs immensely in certain characters from the Piock Pigeon, yet by comparing 

 the several sub-breeds of these breeds, more especially those brought from distant 

 countries, we can make an almost perfect series between the extremes of structure. 

 Thirdly, those characters which are mainly distinctive of each breed ; -for instance, 



