“There was a collective hush in the operating room as we gently removed the clamps from the vessels newly attached to the donor kidney,’’ he wrote. “As blood flow was restored, the patient’s new kidney began to . . . turn pink. There were grins all around.’’

In an autobiography, Murray recalled those moments when it seemed that the transplant team held its breath.

“It was just one of those things that was kind of out of this world, I thought,’’ he told National Public Radio in 2004 for a report on the 50th anniversary of the transplant. “It was something that hadn’t been done before, you knew nothing about it. So I thought about it a long time. . . . My stomach was churning many a morning going to school.’’

Though firm in the reply to his brother before the surgery, Mr. Herrick knew he was risking his life.

To establish that the Herrick twins were as perfect a match as possible, doctors grafted a patch of skin from each brother onto the other to see if it would be rejected. Also, police conducted fingerprint tests to prove the two men were identical twins.

Since then, hundreds of thousands of successful organ transplants have created the impression that such surgery is almost always successful, as it usually is on TV medical dramas. But in 1954, researchers had not yet come up with medications that significantly reduce the chance of organ rejection, and most previous transplant experiments had been conducted on animals such as dogs.

Though always modest about his role in history, Mr. Herrick took an unusual and courageous step into a medical field fraught with mystery.

Ronald Herrick, who suffered from heart ailments that prompted him to retire in 1997, died Monday in the Augusta Rehabilitation Center in Augusta, Maine, where he was recuperating from heart surgery in October. He was 79 and lived in Belgrade, Maine.

And so it was. On Dec. 23, 1954, Dr. Joseph Murray removed a kidney from Ronald and implanted it in Richard. Years later, Murray shared a Nobel Prize for his groundbreaking work. For the Herrick brothers, then 23, the results were more immediate and personal. Ronald gave Richard eight more years of life. Previous transplant recipients had lived for only a few months at best.

“Ron got a note from Richard the night of the surgery telling him to get out of there and go home,’’ said Ronald’s wife, Cynthia. “Ron sent a note back saying, I’m here, and I’m going to stay, and that’s it.’’

As Richard Herrick lay dying in Peter Bent Brigham Hospital 56 years ago, he had second thoughts about trying to make medical history. In another room waited his identical twin, Ronald, who planned to donate a kidney to Richard in what would become the world’s first successful human organ transplant that resulted in long-term survival.

Released first from the hospital, Mr. Herrick returned to his studies at Worcester State Teachers College, from which he graduated with a bachelor’s in education in 1958 and a master’s in education in 1960.

“I was a freshman in college and I went back to school in a couple of weeks,’’ he said in 2004.

The older and more serious of the twins, Mr. Herrick talked about the transplant only if someone asked, and had to be drawn out to make the conversation last more than a few sentences. He taught math for decades in high school, junior high, and college, and kept his hand in farming because he grew up on a family farm and loved the physical work of agriculture.

Richard Herrick became a celebrity of sorts, with news reports chronicling his marriage to a nurse who cared for him after the surgery and the birth of the first of their two daughters.

Ronald Herrick’s life was quieter. A few years after the surgery, he met Cynthia Barnes when a mutual friend asked Mr. Herrick if he could give her a ride to college. They lived in adjoining towns and met when he chauffeured Cynthia and a couple of other students on her first day at Worcester State. The couple married in 1959.

The Herrick twins rarely discussed their historic moment, though, and Mr. Herrick remained reticent after Richard died in March 1963.

“I had to dig out of him about the transplant to get some details,’’ said his wife, who wrote a book for herself and family about her husband’s life. “He talks about how he was out of the hospital in 10 days and he just went back to normal behavior. It was just something he did to save his brother, who was dying. He wouldn’t have done otherwise. He was just very modest about the whole business. That was the kind of person he was, not one to talk about himself.’’

Born in Worcester, Mr. Herrick was the second of four children and graduated from Rutland High School in 1949. An Army sergeant during the Korean War, he was stationed in Germany, running a radio station.

After marrying, the couple lived in Boylston before moving to Mount Vernon, Maine, in 1968. He taught math in high school and junior high in Northborough and Winthrop, Maine, and retired in 1986. Then, he answered an ad for a math instructor at the University of Maine in Augusta and taught there until 1997.

“He was an extraordinary math teacher,’’ said his wife, who added that while conducting research for her book about Mr. Herrick, she found among his records glowing student evaluations, such as one saying “he has endless patience when going over problems.’’

At heart, however, he was a farmer. The Herricks bought a small farm in Mount Vernon, Maine, where they lived until moving to Belgrade about a dozen years ago.

“He loved haying and raising heifers,’’ his wife said. “And the hay had to be perfect before he would bale it.’’

In addition to his wife, Mr. Herrick leaves an older brother, Van, of Barrington, R.I., and a younger sister, Virginia Griffin, of Rutland, Mass.

A memorial service is planned at 2 p.m. Monday in Roberts Funeral Home in Winthrop, Maine. Burial will be in the spring in Mount Vernon Community Cemetery.

Those who knew the Herrick twins well could detect subtle differences in the two. Mr. Herrick was a little bigger, his hair a little darker. Both sang in church “and they would sing hymns, of course,’’ Mr. Herrick’s wife said. “Alone, they had beautiful voices, but together it was just extraordinary because there was just a little difference between them.’’

It was more difficult to tell them apart when they were deep in conversation.

“They kind of became each other,’’ she said. “After a while, you couldn’t tell who was talking — their voices were the same.’’

Glad to have given his twin eight more years, Mr. Herrick in private might show emotion when asked about Richard. In public, he always downplayed the impact on his own life.

“I don’t think about it very often,’’ Mr. Herrick said of the surgery in the 2004 interview with NPR. “It was a long, long time ago. . . . I’ve had one good kidney all these years and I’m still walking around, so I guess it’s worked out all right.’’

Bryan Marquard can be reached at bmarquard@globe.com.

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