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Geneau de Lamarlière in 1892 demonstrated that photosynthetic rate is greater per unit area of leaf surface in sun leaves than in shade leaves. Alexandrov is reported by Maximov ( 1929) to have found higher photosynthetic rates in upper xeromorphic leaves than in lower inserted, less xeromorphic leaves, while Haas and Halma ( 1932) _obtained quicker and better rooting in citrus cuttings which have a high percentage of palisade. Willstätter and Stoll (1918) showed photosynthetic rate increased with chlorophyll content. They Willstätter and Stoll, 1913) recorded data which, by the writer's calculations on the fresh weight basis, showed that sun leaves of Samburns nigra and Acsculus hippocastanum had higher Chlorophyll (a + b) concentrations than shade leaves, while the sun leaves of Platanus acerifolia and Fagus sylvatica had lower concentrations than the shade leaves. Guthrie (1929) showed soybean and radish plants had higher chlorophyll concentrations on fresh weight basis when grown in low light intensity. Ulvin (1934) found soybean plants had a higher per cent of chlorophyll on the wet weight basis when grown in continuous light, but the writer noted no clear trend of his results calculated on the basis of leaf area. A review of literature by Porter (1937) includes some references which support the view that chlorophyll concentration increases with light intensity and many references which do not. Porter, however, found a greater chlorophyll concentration per square centimeter in plants grown under high light intensity.

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Proceedings of the Iowa Academy of Science





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©1939 Iowa Academy of Science, Inc.



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