As a surgeon, Carrel dreamed of keeping tissues alive outside the human body. In the lab, we can grow cultures of bacteria or yeast indefinitely. Although individual bacteria or yeast can age and die, the culture continues to grow and is, in a sense, immortal. But that was not clear for cells and tissues from higher life forms such as us. At Rockefeller, Carrel began a long series of experiments to see whether a culture of cells from a tissue could be kept alive indefinitely. By placing the cells from the heart of a chicken embryo in a special flask,...