Science: Test-Tube Vision

The human eye, says Biology Professor George Wald of Harvard, is like a camera, with a slow film for bright light and a fast film for dim light. At a Cleveland meeting of the Society of Biological Chemists, Dr. Wald told how he and two associates have duplicated in a test tube the action of the eye's fast film.

When the light is reasonably bright, the eye sees by means of millions of microscopic "cones" of the retina. As the light dims, the cones go out of action. Tiny "rods," which are much more sensitive, take over their duties. Only one quantum*...

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