on the death of robert whytt, the professor of the institutes of medicine, cullen accepted the chair, at the same time resigning that of chemistry. in the same year he had been an unsuccessful candidate for the professorship of the practice of physic (medicine), but subsequently an arrangement was made between him and john gregory, the successful candidate, by which they both agreed to deliver alternate courses on the theory and practice of medicine. this arrangement continued until the sudden death of gregory in 1773. cullen was then appointed sole professor of the practice of physic, and he continued in this office until a few months before his death.