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Show Advice on Your Health By Morris Fishbein, Editor, Journal American Medical Association People In Europe are worrying worry-ing nowadays about their ability to see In the dark. The blackout, black-out, which Is now the rule in London, Paris, Berlin and other foreign cities, has made people realize the importance of making their way about In darkness. There Is a well-established relationship re-lationship between the amount of vitamin A in the diet and ability, to see well at night. Before our eyes become adapted to the dark, there Is a short period when everything looks black. Adaptation Adapta-tion to darkness la almost complete com-plete In an hour. During the first World war It was discovered that soldiers had to have sufficient amount of vitamin vi-tamin A to avoid night blindness. Since then, tests have been developed de-veloped to determine whether there is deficiency in vitamin A and whether . night blindness Is present. I At the same time, studies are being made on the ability of people to detect' differences in color at night. The clearness with which any object is seen de pends, of course, on the surrounding sur-rounding objects and on the background. back-ground. Color is seen more easily if set off by Illumination. Red and yellow can be seen more clearly on a white background, back-ground, and green is seen better on a black background. Oa nights when there arelto shadows because of absence of the moon, it is harder to judge distance. There Is also a difference. In the' brightness of colors at night. In daylight, yellow is the brightest color. At night, green Is more easily seen than yellow, blue and red a fact which anyone can find out for himself by walking in a garden gar-den at night. Grass and leaves are seen more easily than the colored flowers. Fortunately, In this country, we are not yet subjected to blackouts. But visits to motion picture houses at night and eight-motoring eight-motoring emphasize the importance im-portance of having sufficient vitamin A to eliminate night blindness. |