At 8:15, Klingemann, gloved, masked and gowned, is positioned at Majewski's left hip, Manson at her right, ready to start the harvest. Each wields an 11-gauge needle, a formidable-looking piece of hardware 4 in. long and about an eighth of an inch in diameter. Working independently, Klingemann and Manson thrust the needles into Majewski's back until they touch bone, and then dig a few millimeters further to tap into the marrow. They attach big plastic syringes to the needles and draw marrow into them. Each pull on the syringes yields just a few teaspoonfuls of bright red spongy fluid. They hand the syringes to an assistant who empties them into a calibrated sack. Working through the original puncture in Majewski's skin, they shift the needles to fresh targets in the bone and repeat the process again and again.

It requires force to pierce healthy bone; this is not a gentle procedure. But thanks to the spinal, Majewski is free of pain. It takes nearly an hour of thrusting and pulling to fill the sack. When a halt is finally called, the level exceeds a quart. Lab tests show that more than enough cells have been collected to re-establish the patient's marrow. And no more should be taken from Majewski. Much of the quart counts as blood loss, and to replace red cells she is given a transfusion of her own blood, which had been drawn weeks earlier.

Manson seals the bone marrow into smaller sacks and takes them to a courier, who packs them into a cooler. The courier also accepts a card from Majewski to the patient. "My prayers are with you," she has written. The courier hurries off to the airport, where security officials have already been alerted, so that guards will not insist on an X ray, which would ruin the marrow.

In the recovery room, Majewski lies bundled in blankets, shivering. A nurse wraps another heated blanket around her. Just before noon, she is wheeled into a regular hospital room. A bouquet, left by the courier, awaits her, along with a card. "Dear Donor," it reads, "I would like to say, Thank you for your help."

By 6 p.m., Majewski is ready to go home. Her back is bandaged and more than sore. Laughing, she says she thinks she is waddling like the comedian Tim Conway. But she has no regrets. Her children, a son, 4 1/2, and a daughter, 2 1/2, greet her with a puppet show. Majewski, looking tired and pale, cannot sit comfortably. But when one of the puppets shouts, "Hello, bone-marrow woman!" she grins.

Her recovery takes a little longer than predicted: the soreness is gone within two weeks, but the fatigue lasts somewhat longer. Knowing what she knows now, would Majewski ever do this again? "Oh, yes,"she says immediately. "I wonder if I'll have a chance to."