OF PIGEONS AND FOWLS. 275 



divergent, and therefore the more proportionately de- 

 veloped varieties. 



Darwin notices, that mention has been made, at in- 

 tervals during the last three hundred years, of several 

 varieties of the Pigeon, like those at present prevailing; 

 and he tacitly assumes, that those varieties have been 

 propagated, for that length of time, and that existing 

 varieties are the pure, lineal descendants of those varie- 

 ties. Now, the existing varieties cannot be traced, to 

 any great period back. They are independently pro- 

 duced from the wild, or rock-Pigeon ( Columba livia). 

 It was impossible, for our fancy varieties, to have 

 survived for the assumed length of time, without an 

 immense amount of crossing. For, individuals, so dis- 

 proportionately developed, as are those of the high 

 fancy breeds, must inevitably die out, unless such viola- 

 tion of the true mutual relation of their parts, is re- 

 trieved by crossing, continually resorted to. The indi- 

 viduals are incapable of close-interbreeding, without 

 injury; and, the further their divergence in character 

 is carried, the more their eventual extinction is hastened. 

 The only way that they may be able to survive, is at the 

 cost of their distinguishing type, namely by crossing. 

 When they have been crossed, interbreeding may be 

 carried on for awhile; after which, to stave off extinc- 

 tion and sterility, they are compelled to take on other 

 characters than those which distinguish their variety, 

 and they suffer, thereby, both the decrease of their 

 special excellence, and a relative abatement of its pre- 

 dominance. In this way only, may varieties, which 

 lack any of the positive characters of their species, and 



