Episode 2 —

In 1903, a Parisian physician discovered how to induce arterial disease in rabbits with a single hormone. Within four years, laboratories on two continents had confirmed this breakthrough—and just as quietly, dismantled it. Episode 2 traces the adrenaline model from its inception to its collapse, revealing not one decisive experiment, but two distinct failures: one of pathological identity and another of causal evidence. These failures compelled the field to concede that it did not truly understand what it was measuring.