This bonus content is a reading from Platypus, the CASTAC Blog. The full post by Awa Diagne can be read at https://blog.castac.org/2026/04/blood-circulation-opening-up-a-closed-system/. About the post: But, blood has never been a single, unified fluid. Among blood’s several components—red blood cells, plasma, platelets—not all have the same exact velocity. When I began developing my dissertation project, which seeks to ethnographically follow blood across myriad institutions, locales and historical periods, I started to observe different models that helped me visualize blood circulation. For me, the question is thus not only how does blood work, but also how is it seen? And how can we better see it?