Table of Contents 



1. Early Ideas on Inbreeding and Crossbreeding .... conway zirkle 1 



2. Beginnings of the Heterosis Concept . . . George Harrison shull 14 



3. Development of the Heterosis Concept H. k. hayes 49 



4. Preferential Segregation in Maize M. M. rhoades 66 



5. Inbreeding and Crossbreeding in Seed Development . . . r. a. brink 81 



6. Physiology of Gene Action in Hybrids w. Gordon whaley 98 



7. Hybrid Nutritional Requirements william j. robbins 114 



8. Origin of Corn Belt Maize and Its Genetic Significance 



EDGAR ANDERSON and WILLIAM L. BROWN 124 



9. Heterosis in Population Genetics . Adrian o a. buzzati-tra verso 149 



10. Fi.xing Transgressive Vigor in Nicotiana Rustica . . harold h. smith 161 



11. Hybridization in the Evolution of Maize . . . paul c. mangelsdorf 175 



12. Biochemical Models of Heterosis in Neurospora . . sterling emerson 199 



13. Nature and Origin of Heterosis th. dobzhansky 218 



14. Plasmagenes and Chromogenes in Heterosis . . . donald f. jones 224 



15. Specificity of Gene Effects m. r. irwin 236 



16. Genetics and Cytology of Saccharomyces .... carl c. lindegren 256 



17. Genetic Implications of Mutations in S. Typhiniurium . . h. h. plough 267 



18. Dominance and Overdominance james f. crow 282 



19. Gene Recombination and Heterosis leroy powers 298 



20. Gene Interaction in Heterosis A. j. mangelsdorf 320 



21. Inbred Lines for Heterosis Tests? Gordon e. dickerson 3vS0 



22. Specific and General Combining Ability .... c. R. Henderson 352 



23. Rotational Crossbreeding and Heterosis L. m. winters 371 



24. Gamete Selection for Specific Combining Ability 



e. l. pinnell, e. h. rinke, and h. k. hayes 378 



25. Monoploids in Maize sherret s. chase 389 



26. Early Testing and Recurrent Selection g. F. sprague 400 



27. Heterosis in a New Population E. j. wellhausen 418 



28. Recurrent Selection and Overdominance fred H. hull 451 



29. Hybrid Vigor in Drosophila John w. gowen 474 



30. Estimation of Average Dominance of Genes 



R. e. comstock and h. f. robinson 494 



Bibliography 517 



Index 537 



IX 



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