In the North, as I have already remarked, a twofold migration ensues upon the abolition of slavery, or even precedes that event when circumstances have rendered it probable; the slaves quit the country to be transported southwards; and the whites of the Northern States, as well as the emigrants from Europe, hasten to fill up their place. But these two causes cannot operate in the same manner in the Southern States. On the one hand, the mass of slaves is too great for ............