Separate culture, 203 
Serum albumin, stereoisomeric forms, 266 
Service, of genetics, 448, 450, 609 
time of and sex-ratio, 543 
Sesqui-hybrid, 73 
combinations, 235, 237, 244, 248 
Sex-chromosomes, 58 66, 1)6, 211, 546 
-factors, 215 
-hormones, 545, 550 
in animals, 536 
-inheritance of, 65, 196, 204, 205, 211 
potency of factors, 217 
Sex-determination, and genotypic constitution, 
218 
in animals, 536 
in honey bee, 211 
in hickory phylloxeran, 211 
in insects, 210 
in man, 538 
in mullein thrips, 211 
metabolic theories of, 544 
Sexes, numerical equality of, 67 
Sex-inheritance, 65 
in plants, 212 
non-disjunction and, 204 
WZ type of, 205 
XY type of, 196 
Sex-linked characters, 197, 208, 209, 538 
in a plant, 214 
factors, 117 
in X-chromosome, 196, 546 
inheritance, 74 
lethal factors in Drosophila, 132 
Sex-ratios, 196, 539 
causes of unusual, 542 
inheritance of, 546 
in man, 540 
Sexual characters, secondary, 214, 548 
Sexuality in plants established, 437 
Shamel, bud selection, 391 
maize, 292 
Sharp, apple breeding, 295 
Shaw and Heller, horns in sheep, 549 
Sheep, Ancon, 462 
Corriedale, 584 
crossbreeding, 515 
diversity of ancestry, 460 
Dorsett, 515, 549 
effect of castration, 549 
horns in, 214, 549 
marking, 602 
Mendelism in, 475 
Merino, 515 
mutations in, 462, 463 
Rambouillet, 463 
sex-determination in, 536 
Shropshire, 463 
Southdown, 463 
sterility in, 552 
Suffolk, 549 
telegony, 564 
Shirreff, cereals, 289 
plant breeding, 437 
selection, 366 
INDEX 
Shull, A. F., mullein thrips, 211 
Shull, G. H., acquired characters, 480 
Bursa, 421 
corn breeding, 356 
factors multiple, 139 
genotypes in maize, 326, 329 
heterosis, 231, ¢ 
inbreeding in maize, 325 
increased yield from hybrids, 353 
Lychnis dioica, 213, 214, 215 
maize, 293, 295 
multiple allelomorphs in Lychnis, 150 
records, 422 
regression, 56 
variation, 369 
Silkworm, larval pattern, 210 
linkage in, 125, 209 
multiple allelomorphs in, 158, 210 
Size, a complex character, 194 
inheritance of, 174, 188 
Skew polygons, 35 
Small grains, composite crossing of, 296 
671 
Smith, L. H., corn breeding experiments, 327, 329 
maize, 292 
Smith and Thomas, pheasants, 558 
Smut fungus, immunity of milo, 416 
Snapdragon, 440 
common, 90, 133 
dimorphic flowers, 275 
variegated, 381 
Soil heterogeneity, correcting for, 431 
criterion of, 430 
Solanum chimeras, 374, 375 
Darwinianum, 377 
dulcamara, 378 
Girtnerianum, 375, 377, 382 
Kolreuterianum, 375, 377, 382 
lycopersicum, 375, 378 
melongena, 378 
nigrum, 375, 378 
proteus, 375, 377, 382 
tubigense, 375, 376, 382 
Soma and germ-plasm, 2, 485, 490 
Somatic cell division, 59 
modifications, 453 
mutations, 386 
segregation a misleading term, 275 
vs. vegetative mutation, 272, 274 
variations, 272 
Somatogenesis, 2, 20 
Somatogenic characters, 480 
Sorghum, collecting stock seed, 341 
origin of varieties, 370 
Southworth, alfalfa, 297 
Species, disease resistance in, 401 
factors in, 219 
homologous factors, 224 
hybridization, 219, 310, 312, 342 
in domestic animals, 515 
hybrids, forms of, 227 
peculiar phenomena in, 249, 542 
sterility in, 234 
vigor of, 230 
in @nothera, 244, 280 
Digitized by Microsoft® 
