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 descendants reverting to an ancestor of foreign blood, removed by a greater number of generations.
Bigarrena, arraza bakoitza, garbiena ere, dozena bat belaunaldiren barruan, gehienik ere hogeiren barruan, haitz-usoarekin gurutzatu da-eta hamabi edo hogei belaunaldiren barruan esan dut, ez baita ezagutzen kasu bat bera ere ondorengo gurutzatua odol arrotzeko arbasoetara atzera itzuli denik, tartean belaunaldi gehiago izanik ere.