The article explores the heuristic meeting between literature and medicine as articulated in the specific case of Jacobsen’s novel Niels Lyhne (1880) and tuberculosis. In the opening pasages, two methodological approaches are presented: A symptomatological, developed by Deleuze, and a cultural phenomenological, developed by Connor. Both tuberculosis in the 19th century, and the work of Jacobsen in a consumptive context, are introduced; and attention is then focused on a narrative sequence in the novel, in which spots – that eat their way into the characters’ relations to each other – are explosively disseminated. Medical science’s discovery of these spots is connected to the emergence of the x-ray, in 1895. By contextualising the novel in contemporary cultural attempts to visualise the hitherto invisible, the article argues that elements in the passage can indeed be read as references to the x-ray avant la letter. In conclusion, the consequences of this surprising assertion are drawn.