When toxic concentrations of the substance make increased dosage dangerous, Edward returns to sensory deprivation, believing it will enhance the effects of the substance at his current dose. Repairing a disused tank in a medical school, Edward uses it to experience a series of increasingly drastic visions, including one of early Hominidae. Monitored by his colleagues, Edward insists that his visions have "externalized". Emerging from the tank, his mouth bloody, frantically writing notes because he is unable to speak, Edward insists on being X-rayed before he "reconstitutes." A radiologist inspecting the X-rays says they belong to a gorilla.