82 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 6 



Mr. Clark has made valuable developments in the technique of 

 special lights useful for studies of plant growth. He has also made 

 important improvements in thermoelectric junction material, having 

 developed a couple of high sensitiveness and at the same time as 

 rugged as ordinary wires of common metals of equal size. With 

 Mr. Fillmen he has constructed much new apparatus for the uses of 

 the Division. 



The work finished or in hand will shortly afford publications of 

 great interest to plant physiologists and others. Individuals of the 

 Division have been of utmost value to the Astrophysical Observatory 

 and other branches of the Institution, assisthig in special problems. 



Respectfully submitted. 



C. G. Abbot, Director. 



The Secretary, 



Smithsonian Institution. 





