Using archival admissions records and case histories of patients at a British asylum from the 1860s to the 1870s, the authors examine the medical certification process leading to the asylum confinement of individuals judged to be "of unsound mind." These institutional texts are, the authors suggest, "occult genres" that function as complex acts of argumentation, whose illocutionary force depends on the success of their felicity conditions. Through the lens of Austin's concept of "uptake," the authors analyze the role of medical certification in the admissions history of two patients at Ticehurst House Asylum in the 1860s-1870s. The authors contend that historical genre analysis plays an important role in the rhetoric of medicine and health, shedding light on the performative power of medical certification, an act essential to the practice of psychiatry. (Contains 5 figures and 17 notes.)