2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



isms, L. B. Clark, and L. A. Fillmen, the successful experiments 

 herein described were conducted under controlled conditions of tem- 

 perature, humidity, and illumination. 



LITERATURE 



As discussed by Meier (1934 b) in more detail, some of the earlier 

 investigators including Wiesner (1874), Artari (1899), Teodoresco 

 (1899, x 9 2 9)> Nadson (1910), and Arthur (1930), who experimented 

 with plants growing under filters of glass and of chemical solutions, 

 as the case may be, without especial attention to the effect of isolated 

 wave lengths, found that their plants displayed more normal develop- 

 ment under blue light than in the other colored lights. Teodoresco 

 (1899, 1934) found that green light caused the poorest chlorophyll 

 development in plants. 



In his research with Scenedesmas acutus, growing under Senebier 

 jars of chemical solutions, Grintzesco (1902) found that the develop- 

 ment of the colonies was more active in the blue-violet than in the 

 red-yellow light. 



Shirley (1929) grew higher plants in a series of houses covered 

 with glass filters transmitting definite spectral regions. He found the 

 entire visible and ultraviolet solar spectrum to be more efficient for 

 the growth of the plants than any small portion of it used. The blue 

 region was more efficient than the red region. 



A. Brooker Klugh (1925), using Wratten light filters whose trans- 

 mission value he had very nearly equalized, found that Volvox aureus 

 and Closterium acerosum reproduced most in red light, less in blue 

 light, and not at all in green light. 



Funke (1931) grew varieties of Sempervivum, Ajuga, and Gle- 

 choma under glass filters which let through different colored lights 

 equalling in intensity about 25 percent of the energy of diffuse day- 

 light. He found that the development in blue was similar to that in 

 full daylight, red had the same influence as darkness, green produced 

 the same phenomenon as red, or reduced development to a minimum ; 

 while in gray (subdued white light) the results were midway between 

 those of red and blue. 



Hutchinson and Ashton (1929) irradiated live specimens of Para- 

 moecium caudatum in isolated wave lengths of a Hilger monochro- 

 matic illuminator operated at a low intensity of illumination. After 

 24 hours' exposure to the red-yellow (6152-5769 A), blue (4359- 

 4348 A), or near ultraviolet (3663-3132 A), stimulation of growth 

 was observed in Paramoecia. Retardation of growth and even death 



