James D. Hardy, 84, the surgeon who implanted the first animal heart into a human, helping pave the way for heart transplants, died Feb. 19 in a nursing home. He had a heart ailment.

He had conducted transplant research and trained generations of surgeons at the University of Mississippi Medical Center. As the center's surgery chief, Dr. Hardy headed teams that did three pioneering operations: the first human lung transplant in 1963, the first animal-to-human heart transplant in 1964 and a double-lung transplant that left the heart in place in 1987.

The 1964 operation -- three years before the first human-to-human heart transplant was performed by South African surgeon Christiaan Barnard -- was the most controversial.

Dr. Hardy had been conducting transplant research in relative obscurity since 1955 and was ready to perform the first transplant of a human heart in 1964.

But when 68-year-old Boyd Rush was admitted to the medical center on Jan. 23, 1964, no human heart was immediately available. Dr. Hardy decided to use the heart of a chimpanzee named Bino.

The newly transplanted heart beat on its own at first, but it was too small to maintain independent circulation, and Rush died after 90 minutes.

In reflecting on the impact of the surgery, Dr. Hardy once wrote that the heart transplant "precipitated intense ethical, moral, social, religious, financial, governmental and even legal concerns."

"We had not transplanted merely a human heart, we had transplanted a subhuman heart," Dr. Hardy wrote.

In all, sheep, baboon and chimpanzee hearts were transplanted into at least four adults between 1964 and 1977; all died within days. In 1984, an infant known as Baby Fae received a baboon heart at Loma Linda University Medical Center in California. She lived for 20 days.

Dr. Hardy served as the first chairman of the medical center's surgery department from 1955, when the teaching hospital opened, until his retirement in 1987.

He was an Alabama native and a 1942 University of Pennsylvania medical school graduate.

His wife, Louise Scott Sams Hardy, died in 2000. All four of their daughters became physicians.