Factors modifying the radio-sensitivity of seeds and the theoretical 

 significance of the acute irradiation of successive generations, 

 Richard S. Caldecott and D. T. North 365 



Discussion of Session IV, I. J. Johnson 405 



Session V: Possibilities for the Future 

 H. F. Robinson, Chairman 



Mutagenic specificity and directed mutation, Harold H. Smith . . . .413 

 Increasing the efficiency of mutation induction, R. A. Nilan and C. F. 

 Konzak 437 



The efficacy of mutation breeding, Walton C. Gregory 461 



Discussion of Session V, Herbert H. Kramer 487 



General Resume of Symposium 

 Resume of symposium, S. G. Stephens 495 



Appendix 

 List of those attending or participating in the Symposium 513 



VI n 



