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CHAPTER IX. 

 DARWIN'S EXAMPLES OP SPECIFIC VARIATION. 



DARWIN'S arguments in favour of the specific 

 variation of species are largely based on the 

 differences between domestic animals and the 

 allied wild species from which he holds they 

 came, and especially among the numerous 

 breeds of domestic pigeons, which, he asserts, 

 are all descended from the rock-pigeon. 



" I am fully convinced," he says, " that 

 the common opinion of naturalists is correct 

 namely, that all [breeds of the pigeon] are 

 descended from the rock-pigeon." l And 

 again, " We have conclusive evidence that 

 the breeds of the pigeon are descended from 

 a single wild species." 2 



Breeds of domestic pigeons differ not only 

 externally in beak, wattles, colour, arrange- 

 ment of feathers, &c., but also in skeleton, 

 as in the number of ribs, vertebrae, &c. So 

 great is the variation, says Darwin, that 



1 Origin of Species, Ed. vi., p. 17. 2 Ibid., p. 392. 



