HEREDITY'S CONFIDANT : McCarty was honored last year at a party at Rockefeller University; the cake celebrates the 60th anniversary of a DNA discovery "that transformed science." Courtesy Zach Veilleux/Rockefeller University Office of Communications and Public Affairs

RICHARD E. MCCARTY remembers what a treat it was to accompany his father, Maclyn, to his lab at the Rockefeller Institute (now Rockefeller University) in Manhattan. One Saturday, poised to add reagent to a bacterial culture, the biochemist speculated aloud: “If I’m right, it will turn blue.” It did. Richard says, “I’ll never forget that grin, that thrill of discovery.” Maclyn McCarty’s influence would be felt not only by his children (sons Richard and Maclyn Jr. became a biology professor and a physical chemist), but also by dozens of scientists who based their research on a paper he co-authored in 1944 that proved that genes are made of DNA, not protein.

McCarty became ill while attending a matinee of The Rivals at Lincoln Center on January 2. He died that evening of congestive heart failure. He was 93.

The son of a mother who recited Shakespeare from memory and a father who was an automobile executive, McCarty mailed only a single college application—to Stanford. He was mentored by the sole biochemistry faculty member James Murray Luck, who founded the Annual Review series of journals and often asked McCarty to review submissions. After completing medical training at Johns Hopkins University, McCarty wound up at the Rockefeller Institute in the laboratory of Oswald T. Avery and Colin McLeod in September 1941. There he worked to isolate and identify the substance that caused pneumococcal bacteria to change from one type into another. The substance—dubbed the “transforming principle”—was identified as DNA, previously not thought to have enough complexity to carry the gene code.

Joshua Lederberg, founder of Stanford’s department of genetics, wrote in his diary, “It set me on the path of looking for DNA transformation in Neurospora, and eventually to my studies of genetic recombination in E. coli”—research that won Lederberg a Nobel prize. “We would have gotten to Watson and Crick’s double helix, but it would have been five to 10 years later,” he explains, adding that the Nobel committee has conceded that not awarding Avery, McLeod and McCarty a Nobel prize for this work was “a significant failure.”

Wanting to play a role in curing disease, McCarty moved on to the study of the streptococcus bacterium. In 1946 he became head of the Laboratory of Bacteriology and Immunology at Rockefeller.

He was the recipient of many awards and honorary degrees, including one from Johns Hopkins presented to him by son Richard, then dean of arts and sciences.

He enjoyed swimming, tennis and classical music, and visited Paris annually for the last 25 years of his life.

McCarty is survived by his second wife, Marjorie Fried; sons Richard and Colin Avery; daughter Dale Dinunzio; stepson Paul Steiner; eight grandchildren; and five great-grandchildren. Son Maclyn Jr. died in 2002.