Experimental Zoology and the Concept of Milieu

This paper explores the evolution of zoology during the Belle Époque, a time marked by the transformation of this discipline toward an experimental approach. By focusing on marine stations, the paper examines how these infrastructures enabled the study of marine organisms in their natural environment, illustrating this shift through the example of the Arago Laboratory and its founder, Henri de Lacaze-Duthiers. The analysis addresses the epistemic functions of marine laboratories, their contribution to contemporary epistemological reflections, and the impact of the concept of milieu in this context.