544 



INDEX 



Heterozygosity and inbreeding depression, 

 linearity of, 459-60 



Heterozygote 



basis for superiority of, 158-60 

 physiological superiority of, 158 

 selective advantage of, 467 



Heterozygote advantage, 347, 349, 350 

 for single loci and chromosome segments, 

 340-41 

 Heterozygote, diploid, 202 



Heterozygous combinations, adaptive sig- 

 nificance, 173 



Heterozygous condition, effects in, 187-91 



Heterozygous inversions, 154 



Heterozygous loci, 341 



Heterozygous populations, variance, 297 



Hexaploid, 389 



Histidine, 278 



Histidine synthesis relation to adenine, 278 



Homocysteine, 215 



Homozygosis, 49, 151 



Homozygosity, 290, 403 



Homozygotes, recurrent selection among, 



470 

 Homozygous abnormal 10 plants, 73 

 Homozygous condition, effects in, 191-97 

 Homozygous diploid dent, 398 

 Homozygous diploid lines, 399 

 Homozygous diploids, 390 

 Homozygous gene arrangements, 153 

 Homozygous lines, 448 

 Honozygous mutant, 157 

 Homozygous normal allele, 157 



Homozygous tester versus reciprocal selec- 

 tion, 342-47 



Homozygous tester lines, 347 



Human endogamy, 2-4 



Athenians, 3-4 



Greeks, 3 



Hebrews, 2-3 



Nordics, 4 

 Human inbreeding, 2-5 



Hybrid advantage, 105 



potential, 339 

 Hybrid, average, 291 

 Hybrid, commercial, 291 

 Hybrid combinations, selection, 27 



Hybrid corn, 15, 16, 118 



and Darwin's influence on W. J. Beal, 10 



development of embryos, 104 



double hybrid, 373 



early explanations, 451-53 



single cross, 373 



vegetative habits of, 30 

 "Hybrid-corn makers," 15 

 Hybrid embryos, 96 



Hybrid growth, 114 



Hybrid and inbred corn grains, growth - 

 promoting activities of extracts from, 

 109 



Hybrid nutritional requirements, 114-23 



Hybrid plants, analyses of starch content of 

 leaves and stems, 108 



Hybrid, reconstructing, 449 



Hybrid results, 433 



Hybrid substance, 243-51 

 fractions of, 247 

 in species hybrids, 243-51 

 tests for, 247 

 tests for similarities and differences, 248 



Hybrid vigor, 14, 15, 98, 108, 112, 118-23, 

 127, 218, 224, 282, 424, 492 



in advanced generations, 180-83 



in artificial plant hybrids, 49 



as associated with high embryo weight, 

 104 



cause of, 13 



chromosomal and cytoplasmic basis for, 

 479-81 



from crossing inbred lines of maize, 50 



definition, 474 



discovery by Mendel, 7 



in Drosophila, 474-93 



effect of chromosome length, 484 



effect of genome components, 482 



of egg yields, 483 



in the endosperm, 85 



as evolutionary accident, 173 



explained by dominance or partial domi- 

 nance, 65 



explanation of, 478-79 



factors effecting, 475 



in field corn, 51 



first described, 7 



genome contributions to, 484—88 



hypotheses to account for, 282, 481, 492 



in maize, 142 



necessary preliminary to, 4 



in production of geniuses, 4 



in plants, 2, 7-8 



as result of allelic interaction, 103 



summary of early knowledge, 13 



in sweet corn, 51 



in Zea mays, 10 



Hybrid vigor development, relation of 

 phosphorus and nitrogen nutrition 106 



Hybrid weakness, 225 



Hybridity 



mechanisms which promote, 152-54, 476 

 optimum, 152 



Hybridization, 423-25 

 ancient, 185 



natural, maize X teosinte, 183-84 

 present-day, 183-85 



of Southern Dents and Northern Flints, 

 132-33 



