Even since Northrop Barkers passing, his family of pigeons could still be around even to-day, and regarded as pure. I can't see where you get 'hundreds of generations' from. Indeed, it would be possible to have pure Barkers around at present,after only 15-20 generations of breeding, maybe less. There ability to 'race' could be questionable, but to make a statement that 'there is no such thing as a Barker' doesn't stand up to scrutiny.