Dr. F. F. Blackman, Professor of Plant 

 Physiology, University of Cambridge, Eng- 

 land. Photosynthesis; Physiology of the cell. 



Dr. W. W. Garner, Plant Physiologist, 

 Bureau of Plant Industry, U. S. D. A., 

 Washington, D. C. Photoperiodism; Min- 

 eral nutrition of plants. 



