This project is oriented around a comparative analysis of cultural production concerning

the metropolitan regions of Los Angeles and Berlin in the twentieth century. While combining approaches toward the history of science and medicine with film and literary studies, this dissertation analyzes the relationship between the increase in invisible risks within large urban centers, and the emergence of illnesses characterized by having undecidable causes (a confusion as to whether they originate from external causes or internal, potentially psychogenic ones.) The body of literature and film addressed in this project, ranging from the turn-of-the-century poetic prose of Rainer Maria Rilke, into 1920's expressionist film and literature in Weimar Berlin, to film noir and Frankfurt School philosophy during the World War II period in Los Angeles and finally to late twentieth century science fiction, explores the cultural effects and implications of the paradigm shift to bacteriology in modern medicine and disease pathology at the end of the nineteenth century. By tracing the experience of undecidable illness within film and literature, this project demonstrates how the paradigm of positivistic disease causation, which resulted from the discovery of the microbe, may have actually generated a radical insecurity within modern society, characterized by anxieties and fears of infection, to the point where many different kinds of psychosomatic, mimetic and psychogenic illnesses also became more widespread. Narrative accounts of undefined illness that were not yet understood scientifically often portrayed experiences of urban community as a collection of anxious impressions of the larger networks of metropolitan infrastructure and the increasing interconnections between multiple individuals which it facilitates, including an invisible dimension of microbiology. These narratives emphasize how urban infrastructure can convey the ineffable presence of "spectral" dangers.