86 The Annual Science Exhibition 



1927. H. J. Muller (genetics). "The Influence of X-rays on Genes and Chromosomes."' 



1928. Oliver Kamm (chemistry). "The Hormones of the Pituitary Gland." 



1929. Arthur J. Dempster (physics). "The Reflection of Protons from a Calcite 

 Crystal." 



1930. M. A. Tuve, L. R. Hafstad and O. Dahl (physics). "The Production of Beta 

 Rays and Gamma Rays by Means of High-Yoltage Vacuum Tubes." 



1931. C. C. Speidel (medicine). "The Study of Living Nerves." 



1932. Henry Eyring (chemistry). "Quantum Mechanics and Chemistry with Particular 

 Reference to Reactions Involving Conjugate Double Bonds." 



! 933- Reuben L. Kahn (medicine). "Tissue Reactions in Immunity; the Specific Re- 

 acting Capacities of Different Tissues of an Immunized Animal." 

 1934. Vera O. Knudsen (physics). "The Absorption of Sound in Gases." 

 J 935- P- W. Zimmerman (plant physiology) and A. E. Hitchcock (botany). "Re- 

 sponses of Plants to Synthetic Growth Substances (Phyto-hormones)." 



1936. W. M. Stanley (chemistry). "Some Biochemical Investigations on Crystalline 

 Tobacco Mosaic Virus Proteins." 



1937. Philip R. White (botany). "Root Pressure — an Unappreciated Force in Sap 

 Movement." 



1938. Norman R. F. Maier (psychology). "Experimentally Produced Neurotic Be- 

 havior in the Rat." 



1939. I. I. Rabi (physics). "Radio Frequency Spectra of Atoms and Molecules." 



The Theobald Smith Awards in Medical Science have been as follows : 



1937. Robley D. Evans. "A Study of Radium Poisoning." 



1938. Charles F. Code. "Histamine in the Blood." 



1939. Albert B. Sabin. "Constitutional Barriers to Involvement of the Nervous System 

 by Certain Viruses." 



The Annual Science Exhibition 



At the meeting held in Kansas City in 1925 the Association had its first 

 science exhibition, managed by Major H. S. Kimberly, of Washington, and 

 Professor Albert Saeger, of Kansas City. There were 10 exhibits by leading 

 manufacturers of scientific instruments, apparatus, biological models, mate- 

 rials and supplies, and exhibits by several agencies of the Government, in- 

 cluding the Bureau of Standards, the Chemical Warfare Service (com- 

 bating boll weevil and other pests), the Bureau of Fisheries, the F'ixed 

 Nitrogen Research Laboratory, the Navy and the Smithsonian Institution. 

 In addition, there were about 25 exhibits by individual scientists and labora- 

 tories. 



At each annual meeting of the Association since 1925 a science exhibition 

 has been held. The mere fact that the exhibits have been held for 16 suc- 

 cessive years proves that they have been of advantage both to the exhibitors 

 and to the Association. Scientists and institutions presenting individual 

 exhibits have shown other scientists in the most efficient way what they are 

 doing and how they are doing it. And those who visit these exhibits may 

 make valuable comments and suggestions to the exhibiting scientists about 



