"Above all, there is no more absurd fallacy than the shibboleth of the "melting-pot." As a matter of fact, the melting-pot may mix but does not melt. Each race-type, formed ages ago, and "set" by millenniums of isolation and inbreeding, is a stubbornly persistent entity. Each type possesses a special set of characters: not merely the physical characters visible to the naked eye, but moral, intellectual, and spiritual characters as well. All these characters are transmitted substantially unchanged from generation to generation."
Race is contextual. It has meant different things at different points in history, always to serve an agenda, because it is a social construct used to divide. In this text, the author makes a case against immigration.. This immigration was not an influx of individuals from countries like Mexico, as we have today, but from European nations. Yet, the author was arguing that the presence of these "newer races," who were not descendants of the original settlers in the U.S, would cause "white supremacy" in the nation to subside. Keep in mind, these too were Europeans being spoken of as inferior. Race has nothing to do with skin color, save the moments when someone in power wants it to do with skin color. Today in the U.S, many Americans are descendants of these immigrants, but somehow, eventually in history, they were racialized as White, and, consequently, have benefitted from that racialization since. Today, also, similar arguments against immigration are being made, even if they are being cast in "race-neutral" terms