J. C. Nott states that interracial marriage will produce infertile couples.
J.C. Nott, "The Mulatto A Hybrid--Probable Extermination of the Two Races if the Whites and Blacks Are Allowed to Intermarry," The Boston Medical and Surgical Journal (August 16, 1843): 29-32
As many of these hybrids are governed by different laws, is it not reasonable that the human hybrid may also have its peculiar laws--may not one of these be (which might inferred from the foregoing data) that the Mulatto or hybrid is a degenerate, unnatural offspring, doomed by nature to work out its own destruction?