gained Baron admission to the Royal Society in 1823. The theory of tubercles, from Jenner and earlier John Hunter, later ran out as misleading; it had opponents in Gaspard Laurent Bayle, René Laennec, and François-Joseph-Victor Broussais. Dupuy, a French veterinarian, had been led two years earlier (1817), and independently of Baron, to adopt the same hydatid theory, to explain the hanging ‘pearls’ or ‘grapes’ that are a common form of tubercle in cattle. The idea was that tubercles were hydatids become solid. Hydatids were then understood to include not only bladderworms, but almost any kind of vesicle filled with fluid. Jenner had been misled by the coexistence of tubercles and true hydatids in the lung of the ox, leading him to adopt the "hydatid theory" of tubercles in general. References Attribution 1786 births 1851 deaths 19th-century Scottish medical doctors 19th-century English medical doctors Fellows of the Royal Society People from Gloucester People from St Andrews