Illustrations played an important role in the articulation of Wundt’s experimental program. Focusing on the woodcuts of apparatus and experimental designs in the six editions of his Grundzüge der physiologischen Psychologie (published between 1873 and 1911), we investigate the uses and functions of illustrations in the experimental culture of the physiological and psychological sciences. We will first present some statistics on the increasing number of illustrations Wundt included in each new edition of his handbook. Next we will show how Wundt (...) managed to introduce the material and literary technologies of physiology into the ‘new psychology’. The distribution of Wundt’s material technology will be further demonstrated by highlighting the crucial role of technicians and instrument-makers. We will use Shapin and Schaffer’s notions of the ‘three technologies’ and ‘virtual witnessing’, combined with Latour’s concept of ‘immutable mobiles’, as analytical tools to explore the strategic aspects of Wundt’s illustrations. (shrink)