Just as Robert Hooke and Antonie van Leeuwenhoek, peering down a microscope, revolutionized cell biology in the seventeenth century, Palade, Porter, and Claude discovered a more abstract way of “looking” inside the cell. First, they burst cells open and spun the contents in a high-speed centrifuge along a gradient of densities. As the centrifuge spun with dizzying velocity, pulling down the cell’s heaviest subparts to the bottom and leaving lighter subparts above, different components of the cell appeared at different gradients along the length of a tube.
