Maclyn McCarty (June 9, 1911 – January 2, 2005) was an American geneticist, a research scientist described in 2005 as "the last surviving member of a Manhattan scientific team that overturned medical dogma in the 1940s and became the first to demonstrate that genes were made of DNA." He had worked at Rockefeller University "for more than 60 years." 1994 marked 50 years since this work's release. McCarty devoted his life as a physician-scientist to studying infectious disease organisms, and was best known for his part in the monumental discovery that DNA, rather than protein, constituted the chemical nature of a gene. Uncovering the molecular secret of the gene in question — that for the capsular polysaccharide of pneumococcal bacteria — led the way to studying heredity not only through genetics but also through chemistry. The team responsible for this feat is known as the Avery–MacLeod–McCarty experiment. He died from congestive heart failure. Early life McCarty was born in South Bend, Indiana. He was the second of four sons; his father was a branch manager for the Studebaker Corporation while it was still a firm for horse-drawn carriages. As an undergraduate at Stanford University, he began his studies in the nascent field of biochemistry, working with James Murray Luck on protein turnover in the liver. He "graduated in 1933 from Stanford, where he majored in biochemistry" and then "went on to earn his medical degree at Johns Hopkins University in 1937." After four more years there and at New York University "he moved to Rockefeller" where he met his future research teammates. Early Rockefeller years MacLeod, over a number of years of research, had resolved several thorny technical issues, so that by the time McCarty arrived at the Rockefeller University, Avery's team had paved the way for McCarty. Their progress over the next three years is described in McCarty's memoir The Transforming Principle, written in the early 1980s. McCarty's arrival at Rockefeller University was also marked by another milestone, namely, the development of a reagent assay to positively correlate DNA with biological activity. In 1944 they published in the Journal of Experimental Medicine about their work. Acceptance of the concept that "genes are DNA" was a slow process. Skepticism and being ignored, at least in the New York research institutions abounded. There were challenges associated with research, which made it especially difficult to attract other investigators to pursue it. Few