470 PLANT PHOTOPERIODISM 



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a probable precursor of protoporphyrin, in the biosynthetic chain of heme and 



chlorophyll. J. Biol. Chem., 202, 801-13. 

 Hamner, Karl C. 1940. Interrelation of light and darkness in photoperiodic 



induction. Botan. Gaz., 101, 658-87. 

 Hand, I. F. 1950. Insolation on clear days at the time of solstices and equinoxes 



for latitude 42°N. Heating and Ventilating, 3 pp. 

 Hillman, William S. 1957. Nonphotosynthetic light requirement in Lemna minor 



and its partial satisfaction by kinetin. Science, 126, 165-66. 

 Hoover, W. H., Earl S. Johnston, and F. S. Brackett. 1933. Carbon dioxide 



assimilation in a higher plant. Smithsonian Inst. Pubis., Misc. Collections, 87. 

 Kimball, H. H. 1935. Intensity of solar radiation at the surface of the earth, 



and its variations with latitude, altitude, season and time of day. Monthly 



Weather Rev., 63, 1-4. 

 Kimball, H. H. 1938. Duration and intensity of twilight. Monthly Weather Rev., 



66, 279-86. 

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cotyl hook of bean seedlings to radiant energy and other factors. Plant 



Physiol, 31, 289-94. 

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growth and pigment synthesis in the bean seedling as related to irradiance 



and wavelength. Am. J. Botany, 44, 15-19. 

 Koski, V. M., C. S. French, and J. H. C. Smith. 1951. The action spectrum for 



the transformation of protochlorophyll to chlorophyll a in normal and albino 



corn seedlings. Arch. Biochem. Biophys., 31, 1-17. 

 Krasnovskii, A. A., and K. K. Voinovskaya. 1957. Reversible appearance of 



red and near infrared absorption bands with photoreduction of chlorophyll, 



protochlorophyll and their analogs. Doklady Acad. Nauk S.S.S.R., 112, 911- 



14. 

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special reference to the tomato. Oregon Agr. Expt. Sta. Bull, 149. 

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in altering the incidence of x-ray-induced chromatid aberrations. II. Reversal 



of the far-red potentiating effect in Vicia by red radiant energy. Radiation 



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 Mohr, Hans. 1956. Die Beeinflussung der Keimung von Farnsporen durch 



Licht und andere Faktoren. Planta, 46, 534-51. 

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Color. Thomas Y. Crowell Co., New York. 

 Parker, M. W., S. B. Hendricks, and H. A. Borthwick. 1950. Action spectrum 



for the photoperiodic control of floral initiation of the long-day plant 



Hyoscyamus niger. Botan. Gaz., Ill, 242-52. 

 Parker, M. W., S. B. Hendricks, H. A. Borthwick, and N. J. Scully. 1945. 



Action spectrum for the photoperiodic control of floral initiation in Biloxi 



soybean. Science, 102, 152-55. 

 Pittendrigh, Colin S. 1956. Perspectives in the study of biological clocks. Per- 



