Abstract
Groups of 2-week-old chicks, fed a leg weakness-producing diet, were exposed daily for 6 weeks to different amounts of sunshine and skyshine between 10:00 A. M. and 1:00 P. M. Growth was followed by weekly weighings. As judged by appearance, attitude, roentgenograms and blood calcium and phosphorus, an average daily exposure to sunshine of 4 to 5 minutes from October, 1929, through March, 1930, and of 2 to 3 minutes through April, 1930, prevented leg weakness. An average daily exposure to skyshine of 62 minutes protected the chicks from October, 1929, to the middle of February, 1930, 28 minutes sufficed from that time through March, 1930, and 23 minutes during April, 1930. We are confident that smaller amounts of radiation would have been effective. Better growth was obtained in the skyshine than in the sunshine animals from October 16 to January 10, indicating that the exposures to direct sunshine were, perhaps, too long.
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