Contents 



Page 

 Foreword V 



Session I: The Nature and Characteristics of Mutations 

 R. P. Murphy, Chairman 



The nature of mutations in terms of gene and chromosome changes, 



John R. Laughnan 3 



Comparison of spontaneous and induced mutations, K. C. Atwood 



(By title only) 29 



Mutation, selection, and population fitness, C. C. Li 30 



Discussion of Session I, M.M. Rhoades 48 



Session II: Mutagenic Agents and Interpretation of Their Effects 



W. R. Singleton, Chairman 



Types of ionizing radiation and their cytogenetic effects, Arnold H. 



Sparrow 55 



Chemicals and their effects, Charlotte Auerbach 120 



Effects of preirradiation and postirradiation cellular synthetic events 

 on mutation induction in bacteria, Felix L. Haas, Charles O. 

 Doudney, and Tsuneo Kada 145 



Discussion of Session II, Bernard S. Strauss 173 



Session III: Evaluation of Mutations in Plant Breeding 

 G. F. Sprague, Chairman 



Use of spontaneous mutations in sorghum, J. R. Quinby 183 



Use of induced mutants in seed-propagated species, Horst Gaul .... 206 

 The use of induced mutations for the improvement of vegetatively 



propagated plants, Nils Nybom 252 



Discussion of Session III, W. M. Myers 295 



Session IV: Utilization of Induced Mutations 

 F. L. Patterson, Chairman 



Screening methods in microbiology, Thomas C. Nelson 311 



Methods of utilizing induced mutation in crop improvement, James 

 MacKey 336 



vii 



