for an ancient progenitor may have acquired through natural selection some one modification in structure, and, after thousands of generations, some other and independent modification; and these two modifications, having been transmitted to a whole group of descendants with diverse habits, would naturally be thought to be in some necessary manner correlated.
izan ere, antzinako arbaso batek hautespen naturalaren bidez beregana zezakeen eraldaketaren bat bere egituran eta, milaka belaunaldi geroago beste eraldaketa independente bat;