APPENDIX 9 



REPORT ON THE DIVISION OF RADIATION AND 

 ORGANISMS 



Sm : I have the honor to submit the following report on the activi- 

 ties of the Division of Radiation and Organisms during the year 

 ended June 30, 1939 : 



On May 1, 1929, the Division of Radiation and Organisms was 

 organized for the purpose of undertaking "those investigations of, 

 or directly related to, living organisms wherein radiation enters as 

 an important factor." This year marked the tenth anniversary of 

 the Division. During these 10 years the Division has grown in its 

 physical equipment and its personnel. Much of its research has been 

 distinctly fundamental jn nature, and the counsel of its members is 

 being sought constantly on technical and research problems in the 

 field of radiation as related to living organisms. Throughout this 

 period most important financial aid has been given by the Research 

 Corporation of New York. 



During the past year the activities of the Division have been focused 

 largely on problems dealing directly or indirectly with photosynthesis, 

 factors influencing plant growth, and the stimulative action of ultra- 

 violet radiation. 



PHOTOSYNTHESIS 



Work is being continued on the mechanics of photosynthesis. 

 Experimental evidence has been obtained by Dr. McAlister which 

 indicates the formation, during the process of photosynthesis and not 

 before, of a material in relatively large quantities which combines with 

 or absorbs carbon dioxide. The experimental evidence indicating the 

 existence of this carbon dioxide-combining "intermediate" is the 

 flow of a relatively large amount of carbon dioxide into the leaf after 

 the light reaction is stopped, i. e., in darkness immediately following 

 a high rate of photosynthesis. This "pick-up" is of an order of mag- 

 nitude greater than any possible plant uptake due to solubility or 

 other strictly physical processes. It occurs far too fast to be due to 

 the action of a "buffer solution." Hence it appears to be due to a 

 compound or "intermediate" that operates in the process of photo- 

 synthesis. That it is chlorophyllous in nature is suggested by the 

 fact that the largest pick-up so far obtained is of the order of the 

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