Archibald Garrod joined the staff of Barts in 1884. In 1902, he published his classic paper in the Lancet where, for the first time, a disease (alkaptonuria) was shown to be caused by heredity. Garrod went on to study other metabolic disorders, including the pigment disorders porphyria; the cause of George III's madness; and albinism. In his book, Inborn Errors of Metabolism (1909), Garrod described an important new class of diseases which were genetic, not bacteriological in origin, with a genetic factor causing a deficiency in a certain enzyme which led to a block in the chemistry of normal metabolism.