Frozen Bugs

The electron microscope is man's sharpest artificial eye, but it can examine only dead, dry objects. The electron stream that it uses instead of light requires a high vacuum, so no water or water vapor can remain in the instrument. The usual method of preparing microorganisms or viruses for electron microscopy is to dry them at ordinary temperatures before putting them in the instrument.

The trouble with this method is that the bodies dry flat, squashing down to thin, distorted films. Last week Professor (of biophysics) Robley C. Williams of the University of California told of a better method. He puts a film of collodion on a copper disk cooled with liquid air (temp. ~377-6DEG F.). Then he sprays his microorganisms on the cold film. They freeze solid in a flash. When he pumps the air from around them, their moisture passes directly from ice to vapor, leaving their empty husks in the exact shapes they had at the instant they were frozen.

Dr. Williams hopes that this freeze-dry method will reveal new information about bacteria and viruses. He hopes, for instance, to freeze viruses in the very act of attacking victim cells.

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