How big is a cell? Or, how big are any of the parts of a cell as one sees them through a microscope? Scientists today are as far away from the answer to these questions as they were over a century ago because the available technical means are still inadequate to cope with the problem. The questions were asked immediately with the discovery that living systems comprised cells, which were found to be basic units that anyone could see in plants and animals. Everywhere one looked in the plant and animal kingdom were cells of all manner and shape, and in an era that was dominated by the orderliness superposed on the natural world by Newtonian mechanics it seemed natural to want to measure cells.