APPENDIX 9 



REPORT ON THE DIVISION OF RADIATION AND 

 ORGANISMS 



Sir: I have the honor to submit the following report on the 

 activities of the Division of Radiation and Organisms during the 

 year ended June 30, 1941 : 



The operations of the Division have been financially supported by 

 funds of the Smithsonian Institution and in part by a grant from 

 the Research Corporation of New York. 



For several months during the past year actual work in the 

 laboratories was suspended during the construction of a new sewer 

 system and the preparation and actual work of electrical rewiring 

 throughout the building. Also three of the laboratories and the 

 machine shop were repainted. 



Considerable time has been given by members of the division in 

 the planning and construction of an exhibit now on display as part 

 of the "Index Exhibit" in the Main Hall of the Smithsonian Building. 

 A detailed description of this exhibit appears in the July 1941 

 number of the Scientific Monthly. 



INFLUENCE OF RADIATION ON RESPIRATION 



Following the preliminary experiments and improvement in tech- 

 nique as reported last year on the project dealing with the genesis 

 of chlorophyll and the beginning of photosynthesis, many data have 

 been obtained on the respiration of etiolated barley seedlings. This 

 information is highly desirable because of its bearing upon photo- 

 synthesis as measured by the gaseous exchange method. Further- 

 more, a comprehensive review of the literature on respiration as 

 affected by radiation is being completed and will soon be made 

 available. 



The rate of respiration (carbon dioxide evolution) of etiolated 

 barley seedlings (i. e., seedlings grown in complete darkness and 

 devoid of chlorophyll) increases following illumination, whether 

 measured in dark or in light. Under favorable conditions this rise 

 amounts to as much as 20 percent of the previous dark rate and is 

 maintained for at least 7 hours after the light exposure. 



Ill 



