KINETIC ANALYSIS OF PHOTOPERIODISM 



453 



Fig. 6. Range of light intensities encompassed by the natural environ- 

 ment and biological photoresponses. Literature sources are: Sunlight, 

 Moon (1940), "Hand (1950), Kimball (1935); Moonlight, Kimball 

 (1938); Vision, Committee on Colorimetry (1953); Photosynthesis, 

 Hoover, Johnston, and Brackett (1933); Chlorophyll Synthesis, Koski, 

 French, and Smith (1951); Photoperiodism. Withrow and Benedict 

 (1936); and Photomorphogenesis, Klein, Withrow, and Elstad (1956). 



