PREFACE vii 



headings. The early history and development of the heterosis concepts and 

 the cy to logical aspects of the problem occupied the first week. The contribu- 

 tions of physiology, evolution, and specific gene or cytoplasmic effects to the 

 vigor observed in hybrids were dealt with the second week. The third week's 

 meetings covered postulated gene interactions, as dominance, recombination, 

 and other possible gene effects. During the fourth week breeding systems and 

 methods of utilizing and evaluating heterosis effects were considered. In the 

 final week the students considered the problems that lie ahead and recent 

 methods of meeting them. 



At each daily conference the speaker of the day presented a formal morn- 

 ing lecture covering his subject. In the afternoon, he led a conference session 

 on the subject of the morning lecture. At this time, all present had an oppor- 

 tunity to participate. 



Accompanying, and as a supplement to the Heterosis Conference, a 

 Methods Workshop was held from July 3 to July 13. The Workshop was de- 

 voted to recent techniques for evaluating the kinds of data which occur fre- 

 quently in animal breeding experiments. Workshop meetings were organized 

 by Professor R. E. Comstock of North Carolina State College and Professor 

 Jay L. Lush of Iowa State College. 



The meetings were led by men from several institutions besides Iowa 

 State College. Professors Oscar Kempthorne, Jay L. Lush, C. R. Henderson, 

 G. E. Dickerson, L. N. Hazel, F. H. Hull, A. E. Bell, A. M. Button, J. Bruce 

 Griffing, C. C. Cockerham, F. H. W. Morley, R. M. Koch, and A. L. Rae 

 contributed much to this phase of the program. It is with regret that it is 

 impossible to present the meat of the methods presented and developed in 

 the Workshop and the afternoon discussions. To many, this material con- 

 tributed much to the merit of the conference and the use to which the results 

 were put later. 



In the field of worth-while living, as well as to see heterosis in operation, 

 conferees were guests, on various weekends, of three nearby companies putting 

 heterosis to the practical test of commercial seed stock production in crops 

 and live stock — the Ames Incross Company, the Farmers Hybrid Corn 

 Company, and the Pioneer Hi-Bred Corn Company. 



Finally, the organization of the conference was the product of the joint 

 effort of the genetic group of Iowa State College. This group transcends all 

 departmental lines having as the common interest what goes on in inher- 

 itance. They were Jay L. Lush, G. F. Sprague, Oscar Kempthorne, S. S. 

 Chase, Janice Stadler, L. N. Hazel, A. W. Nordskog, Iver Johnson, W. A. 

 Craft, J. Bruce Griffing, and John W. Gowen. 



In last analysis it was the interest of the audience and their participations 

 in the discussions that made the Conference worth while. The papers cover- 

 ing material presented by the leaders of these discussions follow. 



