In “Plantation Hygiene,” published in the Southern Agriculturist, Merrill states that all plantations should be provided with a hospital. He calls for measures such as adequate ventilation and a balanced diet. He argues that adequate health care makes for stronger laborers. Also significant to note is that Merrill identifies "Negro physicians" as a particular medical specialty, because of the polygenesis theory, which is an emerging pseudoscientific argument that Black and white people are separate species.