in 1736 he began medical practice in hamilton, where he rapidly acquired a high reputation. he also continued his study of the natural sciences, especially of chemistry. from 1737 to 1740 william hunter was his resident pupil, and at one time they proposed to enter into partnership. in 1740 cullen was awarded the degree of md from glasgow university. in 1741, he married and started his family. he became ordinary medical attendant to james douglas, 5th duke of hamilton (1703–43), his family, and his livestock. in 1744, following the duke's death, the cullens moved to glasgow.