Science: Cells Alive

One of the toughest problems in biology is how to take a microscope picture of a healthy living cell. Most tissue cells, whether animal or vegetable, are transparent to ordinary light. To make them visible they must be stained, and the stain either kills them or sickens them. They can be seen with special ultraviolet microscopes, but strong ultraviolet is also deadly to cells; only the picture of a tiny corpse appears in the photomicrograph.

Dr. Robert Barer of Oxford University, England, is sure he has licked the problem. He uses monochromatic (single wave length) ultraviolet at an intensity which is too low to hurt the cell. It is also too feeble to make a useful impression on a fluorescent screen or photographic plate, so Barer focuses the invisible image, enlarged with a reflecting microscope to about three inches in diameter, on a screen. Then, by means of a rapidly revolving mirror, he “scans”‘ the image, throwing the ultraviolet light from a narrow slice of it into a photomultiplier tube. The faint glimmer of ultraviolet is thus changed into a fluctuating electric current that is powerful enough to form a bright curve on the face of a cathode-ray tube.

A series of these curves taken from successive slices of the image can be turned into patterns of light and shade, and built into a picture in ultraviolet of the still-healthy cells. But Dr. Barer is after bigger game. The curves show how much of the ultraviolet is absorbed by each region in the cell. These figures, in turn, give a strong hint of what chemicals are present in each of the cell’s parts. Dr. Barer hopes that his apparatus will allow biologists to watch fragile, transparent cells as they live their normal lives and to chart the chemical reactions that take place inside them. When science can take a closer look at living cells, it will know much more about the delicate, mysterious chemical processes that are called life.