The Volkskörper, literally translated as either "national body" or "body national", was the "ethnic body politic" in German population science beginning in the second half of the 19th century. It was increasingly defined in terms of racial biology and was incorporated into Nazi racial theories. After 1945 the term was largely used synonymously with population in anthropology and geography (similarly to ethnicity or nation-state). In political parlance, however, the Volkskörper served as a metaphor for an organic and biological understanding of the unity between the Volk and the Volksgemeinschaft, its broader society. In German politics during the 19th and 20th centuries, it was used especially in anti-Semitic and racial hygiene texts to semantically differentiate the Volk, conceived as a biological and racial unit, from so-called "parasites", "pests" and "diseases". In this naturalistic sense "excretion" was construed in such a way as to define elements of the population as disease-causing and therefore needing to be expelled. The metaphor of the body national was therefore closely related to the Nazi regime's racial system and justified the enactment of policies like Aktion T4.