14 SMITHSONIAN^ MISCELLANEOUS COLLECTIONS VOL. 87 



showed some general growth habits common to both normal and 

 shade-grown plants. The internodes were larger, the leaves larger, 

 and the water requirement less than in plants grown under the 

 visible radiation alone. 



A marked decrease in chlorophyll occurred in the leaves of the 

 tomato plants grown under the full visible and infra-red range of 

 wave lengths. A distinct yellowing and death was noted in extreme 

 cases. It appears that, if not actually destructive, this infra-red region 

 of the spectrum is of little or no benefit to chlorophyll formation. 



It would appear that normal growth of the tomato plant can be 

 obtained under artificial light conditions where the infra-red is cut 

 off and the intensity great enough. 



From a review of the literature and from the results obtained in 

 these experiments with the tomato plant it appears that the near 

 infra-red region of the spectrum is of considerable biological 

 importance. 



Furthermore, experiments comparing the effects of different por- 

 tions of the visible region must be scrutinized for the possible 

 presence of different amounts of near infra-red. 



LITERATURE CITED 



(1) Arthur, John M. 



1932. Red pigment production in apples by means of artificial light 

 sources. Contrib. Boyce Thompson Inst., vol. 4, pp. 1-18. 



(2) Arthur, John" M. 



1932. Some effects of visible and invisible radiation. (Abstract) Torreya, 

 vol. 32, pp. 107-108. 



(3) Arthur, John M. ; Guthrie, John D. ; and Newell, John M. 



1930. Some effects of artificial climates on the growth and chemical 



composition of plants. Amer. Journ. Bot., vol. 17, pp. 416-482. 



(4) Atkinson, Geo. F. 



1893. Oedema of the tomato. Cornell Agric. Exp. Sta. Bull. 53, 

 pp. 101-128. 



(5) Brackett, F. S., and Johnston, Earl S. 



1932. The functions of radiation in the physiology of plants. I. General 

 methods and apparatus. Smithsonian Misc. Coll., vol. 87, no. 13, 

 pp. I-IO, I pi. 



(6) BuRK, Dean; Lineweaver, Hans; and Horner, C. Kenneth. 



1932. Iron in relation to the stimulation of growth by humic acid. Soil 

 Sci., vol. 33, pp. 413-452. 



(7) Funke, G. L. 



1931. On the influence of light of different wave-lengths on the growth 



of plants. Recueil des travaux bot. Neerlandais., vol. 28, pp. 



431-485- 



(8) Guthrie, John D. 



1929. Effect of environmental conditions on the chlorophyll pigments. 

 Amer. Journ. Bot., vol. 16, pp. 716-746. 



