INDEX 



551 



Sib crosses, advantage over self-fertiliza- 

 tion, 29 

 Sicklemia, 295 



Single cross 



distribution, 145 



estimation of the value of, 367 

 Single cross yields versus double cross, 58 

 Single gene heterosis, 155, 282 

 Single locus heterosis, 102 

 Somatic antigens, 268 

 Southern Dents, 127, 129, 131 



characteristics of, 136 



distribution of chromosome knobs, 130 



ear of, 133 



historical record, 128 



kernel of, 133 



and Northern Flints, crosses between, 137 



and Northern Flints, differences between, 

 136 



seeds of, 134 



shanks of, 134 



typical ears of, 134 



typical plants, tassels, and staminate 

 spikelets of, 135 

 Species specific, 254 



Specific combinabiiity, 452 



heritability of, 451 



recurrent selection for ,454-57, 470-73 



working definition, 454 

 Specific combining ability, 352-53, 487-91 



gamete selection for, 378-88 

 Specific and general combinabiiity, relative 



importance, 451 

 Specific and general combining abihty, 



352-70 

 Specificity of gene effects, 236-55 

 Spindle, 74 



Spores, mating types, 257 

 Sporophyte, 389 



Standard inbreds, 233 

 conversion, 233 



Statistics, role in genetical research, 494 



Sugar cane 



cross-fertilization in, 320 

 male sterility in, 320 

 propagated asexually, 320 

 reaction toward inbreeding and out- 

 crossing, 320 

 self-pollination in, 320 



Sulfonamide-requiring character 

 biochemical basis for, 207-10 

 heterocaryotic suppression of, 203-7 



Sulfonamide-requiring strain, 212, 215 

 Sulfonamides, 111 



Sulphur compounds, utilization by various 

 auxotrophs, 276 



Sulphur containing compounds, reactions, 

 277 



Super-dominance, 282 

 Superior mutant, 323 



Supernumerary chromosomal fibers, 72 



unorthodox formation, 72 

 Suppressor heterocaryosis, 212-15 

 Suppressor genes and sulfonamide utiliza- 

 tion, 213 

 Suppressor mutant strains, growth curves, 



214 

 Suppressor mutants, 203 

 Swine and corn inbreeding 

 degree of heterozygosity, 338 

 effectiveness of continued phenotypic 

 selection, 338 

 Swine, heterozygote advantage for single 

 loci and chromosome segments, 340-41 

 Swine inbreeding experiments, results, 331- 



32 

 Synapsis, 69, 115 

 Synthetic varieties, 432 

 formation, 433 



Synthetics, 448 



estimating number of lines to use, 432 

 propagated through open-pollination, 426 



Teosinte {See also Maize) 

 ecology, 183 

 variation, 184-85 



Teosinte germplasm, 419 

 Terminal chiasmata, 68 

 Test crosses, 408 



Tester lines, partially inbred, use of, 347-48 

 Tetrad analysis, 258 

 Thiamin pyrophosphate, 1 10 

 Thiamine, 118 

 "Three-way" crosses, 40, 42 

 Tobacco, crosses between varieties and 

 species, 49 



Tomato hybrids 



number of fruit that ripens, 309 



weight per fruit, 309 



yield of ripe fruit, 309 

 Tomatoes, main and component characters, 



305-10 

 Tomato roots, 116 

 Topcross combining ability, 406 

 Transgressive characteristics, 172 

 Transgressive inbred, 161 

 Translocation point, 68 

 Triphosphopyridine nucleotide, 110 

 Triploids, 389 

 Tripsacum, 419 

 Tripsacum hypothesis, 138 

 Trivalent associations, 69 



Univalents, 69 



