As an example, here's a paragraph from R.W. Shufeldt's 1907 work, The Negro a Menace to American Civilization:
In the negro all passions, emotions and ambitions are almost wholly subservient to the sensual instinct, and that quite apart from the sexual or procreative instinct, for an individual of this race is yet to be found who has ever had congress with the opposite sex, having only in mind the making of a child. They copulate solely for the gratification of the passion--for the erotic pleasure it affords them. In other words, negroes are purely animal, that is, in the sense of quadrupedal animals, in this respect. Nor should we expect anything different from this; civilization and progressive civilization are altogether meaningless to them, consequently posterity has practically no interest for them. They live in the present, and being essentially without morals, and, as a rule, being equipped far above the average man for sensual indulgences, he gives that side of his nature full sway, when no restrictions of any kind whatever are present to hinder.
Shufeldt thought sex should only be for making babies, so he has to say that Negroes don't. They fuck for fun! Can you imagine anything more heinous?