INDEX 



549 



Polygenic characters 



heterosis in, 159 



selective advantage of, 158 

 Polygenic inheritance, 153 

 Polygenic mutations, induction of, 160 

 Polymorphism, 154 

 Polyploid series, 257 

 Polyploids, 321, 389 

 Pop corn, 418 



Population 



adaptation to environment, 151 



definition, 149 



evolutionary factors responsible, 150-52 



genetic structure, 150 



as natural unit, 150 

 Population genetics of heterosis, 149-60 

 Population variance, 292-94 

 Populations, natural, genetic structure, 152 

 Position effect, kinetic theory of, 78 

 Postgermination growth in plants, 105 

 Potassium availability, studies on tomato 



inbreds and hybrids, 107-8 

 Potence in intervarietal hybrids, 166 

 Potence in maize X teosinte, 188-91 

 Potential heterosis, 140 

 Prolificacy, 335 

 Predicting combining ability, 59 



Preferential segregation 

 factors responsible, 68 

 and neo-centric activity, 78 



Preferential segregation in maize, 66-81 



Pre-Mendelian hybrids, 11 



Prepotency, 451 



Post-Mendelian investigations, 2 



Proembryo, 87 



Progeny variance, genetic nature of com- 

 ponents, 498 



Progressive evolution, 265 



Propagation, vegetative, 12, 13 



Prophase II, early, 74 



Prophase II, late, 74 



Prototrophic organisms, 269 



Pseudo-alleles, 254, 295 



Pseudoheterosis, 223 



Pseudo-overdominance effect, 325, 458, 501 



Pure lines and their hybrids, relationship 

 between, 28 



Pure line method in corn breeding, 28 



Pure line method of corn production, 44 



Pure strains, 24 



Pyridoxal phosphate, 110 



Pyrimidineless mutant plus suppressor al- 

 lows growth, 217 



Pyruvate carboxylase, 110 



Quadruple crosses, 44 

 Quantitative inheritance, role of limiting 

 factors, 324-27 



Random mating, 432 



Recessive characters, deleterious, 100, 323 

 Recessive and dominant lethals, 160, 480 

 Recessive genes, 225-26 

 Recessiveness and deleterious effect, corre- 

 lation between, 284 



Recessives, 11 



Reciprocal cross, 28 



Reciprocal effects, 487 



Reciprocal recurrent selection, 415-17 



with inbreeding, 457 

 Reciprocal selection, 351 

 Reciprocal testing, method of, 443 

 Recombination, 267 



Recombination tests in Salmonella, 274-75 

 Reconstructing a hybrid, 449 

 Recurrent selection, 351, 411-12, 451-73 



effectiveness of, 467-70 



for general combinability, 470 



among homozygotes, 470 



meaning, 452 



as a method for modifying chemical com- 

 position, 411 



as a method for modifying combining 

 ability, 411 



in modifying combining ability, 415 



for specific combinability, 454-57, 470-73 

 Recurrent series, 412 



Recurrent selection and early testing, 400- 

 417 



Recurrent selection and inbreeding in modi- 

 fying oil percentage in corn, 411-12 



Recurrent selection and overdominance, 

 451-73 



Red blood cells, 239 



Regression, partial, offspring on parents, 

 463 



Regression trends, 461 



Regressions, genetic interpretation, 462-65 



Relic genes, 424 



Reproduction, asexual, 47 



Repulsion linkages, 502 



Reversed heterosis, 225 



Residual heterozygosity in inbreds, 31 



Rh substance, 242 



Root cultures, 109-10 



Root growth pattern, relation to heterosis, 

 106 



Rotational crossbreeding, 374-77 

 and heterosis, 371-77 



Rust, 424 



