Washington also mentioned the exploitation of black slave bodies when she talked about the mistreatment of black infants during the 1800s. Sims used their bodies for tetany experiments.[4] Sims determined through his research that the cause of tetany in the babies was a result of the movement of skull bones during birth. In order to test his theory, he took a black baby and, using a shoemaker's tools, opened the baby's brain based on his belief that black babies' skulls grew faster than the skulls of white babies, preventing their brains from growing or developing.