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A. B. LUCKHARDT, Ph.D., M.D.; J. B. CARTER, B.S., M.S.
JAMA. 1923;80(11):765-770. doi:10.1001/jama.1923.02640380029009.
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During the early part of 1908, severe losses were sustained by carnation growers shipping their products into Chicago, because of the fact that these flowers, when placed in the greenhouses, would "go to sleep," whereas the buds already showing petals failed to open. Crocker and Knight1 of the Hull Botanical Laboratory immediately undertook the study of the effect of illuminating gas on flowering carnations, the results of which showed that ethylene, which forms approximately 4 per cent, of the gas, is the chief constituent that determines the toxicity of the gas for plants. Their investigations showed that one part of ethylene in 2,000,000 parts of air caused the already open flowers to close, on twelve hours' exposure, whereas one part in 1,000,000 prevented the opening of buds already showing petals. Neljubow,2 who had previously studied the effects of ethylene on etiolated seedlings of peas and other legumes, showed


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