born Oct. 21, 1877, Halifax, N.S., Can.
died Feb. 20, 1955, Nashville, Tenn., U.S.
Canadian-born U.S. bacteriologist.
He studied at Colgate University before taking a post at New York's Rockefeller Institute Hospital. There he discovered transformation, a process by which a change could be introduced into bacteria and passed on to later generations of transformed cells. He and his coworkers reported in 1944 that the substance that caused the transformation was DNA, the cell's genetic material. The discovery thus opened the door to deciphering the genetic code .