Oswald Avery (1877-1955), US bacteriologist. Avery was born in Canada, but was educated in New York. He qualified in medicine in 1904, and entered bacteriology research in 1913. In 1928, he became intrigued by Griffith's claim that a non-virulent, unencapsulated pneumococcus bacterium could be transformed into a virulent, encapsulated form in the body of a mouse, simply with the presence of dead encapsulated bacteria. Avery repeated this work at length, and in 1944 announced that the transformation was caused by deoxyribonucleic acid (DNA). Although Avery (wisely) didn't go on to claim that genes are simply DNA, his work was of great importance to later workers.