This paper explores the formative role of substances of intoxication in the social and scientific establishment of the biological subject in late nineteenth-century Germany. Sourcing the emergence of substances of intoxication as “vital substances” from Brunonianism, this narrative traces their initial significance for Romantic physiology, followed by their rejection from neo-mechanical scientific physiology. Emphasis is placed on late nineteenth-century psychological research on the effects of intoxicants on the mind as the site of a dynamic encounter between theories of the mind (...) and the body, particularly through Kraepelin’s concept of intoxication as model psychosis, and his related research. The biological subject, here, is anti-vitalistic, and, yet, conceptually distinct from neo-mechanism. (shrink)