William Bateson’s “rediscovery” of Mendel’s work in 1900 converted him into a believer in genes. Bateson coined the term genetics in 1905 to describe the study of heredity. Wilhelm Johannsen (left) coined the term gene to describe a unit of heredity. Johannsen visited Bateson at his house in Cambridge, England; the two became close collaborators and vigorous defenders of the gene theory.