INDEX 
Hybridization in maize, 295 
in sweet peas, 309 
in the rose, 310 
of alfalfa, 348 
of maize, 344 
of wheat, 345, 347 
pollination, 343 
practised by Thaer, 288 
in China, 287 
in Holland, 287 
in Italy, 287 
protection of flowers, 344 
species, 219, 249, 342, 351, 515 
systematic procedure, 343 
variety, 248 
Hyde, fertility, 553 
Hydrogen ion concentration in plants, 413 
Hyperchimera, 375 
Hypothesis of factor contamination in heterozy- 
gotes, 190 
of factor variability, 192, 193 
of reaction systems, 242, 248, 575 
Ideal of breeder, 342 
Ideas, erroneous in breeding, 449 
Illinois corn-breeding experiments, 327 
role of selection in, 329, 333 
Immunity, acquired, 528 
breeding for, 529 
indirect, 528 
to disease, 404, 527 
Inbreeding, as a system, 581 
coefficient of, 598 
curves of, 600 
Darwin’s idea of, 553 
in maize, 325 
not harmful in itself, 553 
Increased vigor in species hybrids, 230 
Index numbers, selection, 334, 502 
Individual plant selection, 340 
Infection of male, 571 
Infectious chlorosis, 381 
Ingersoll, increased yield from hybrids, 354 
Inheritance, blending, recognized by Castle, 188 
critical problem of, 4 
intensity of, 459 
of acquired characters, 6, 480 
of aleurone color in maize, 83, 105 
of black and curved in Drosophila, 113 
of coat color in horses, 467 
in mice, 94 
of coat characters in guinea-pigs, 86 
of corolla length in tobacco, 181 
of defects, 524 
of disease, 522 
of effects of use and disuse, 491 
of endosperm texture in maize, 84 
of fecundity in fowls, 560 
of flower characters in snap dragons, 90 
of larval pattern in silk worm, 209 
of pigmentation in hooded rats, 186 
of predisposition to disease, 523 
Inheritance of sex, 65, 196, 204, 205, 211, 212 
of size differences, 185 
of unusual gex-ratios, 546 
of vestigial wings, 87 
of white-eye color, 74 
quantitative, 174, 185, 194 
three types recognized by Castle, 189 
Insects, grafted, 382 
injurious, 400 
sex-determination in, 210 
Interactions, types of factor, 167 
Interference, 122 
Intermediate, condition in F; species hybrids, 227 
expression in the hybrid, 147 
Internal secretions and dimorphism, 276 
Intergeneric hybrids, 296 
Intersexes, in gypsy moth, 217 
in Lymantria, 216 
Interspecific hybrids, 296, 297 
Introduction, seed and plant, 299 
Investigation, genetic, 4, 591, 609 
methods of conducting, 591 
need of biochemical, 413, 485 
of a natural chimera, 378 
Isolation of pure lines from populations, 256 
J 
Janssens, crossing-over mechanism, 115 
Jeffrey, sterility of hybrids, 234 
Jennings, development, 10 
regression, 56 
Jesenko, wheat-rye hybrids, 236, 237, 238 
Johannsen, bean mutations, 367 
gene, 71 
genotype conception, 329 
mathematics in biology, 56 
Princess bean, 250 
pure lines, 7, 252, 253, 254, 255, 256 
regression, 56 
selection, 250, 366 
summary of Mendel’s results, 79, 80 
variation, 439 
Johnson, tobacco, 418 
Jones, A. N., grains, 296 
Jones, D. F., heterozygosis, 559 
vigor of hybrids, 231, 326, 364 
Jones and Hayes, corn. crossing varieties, 360 
tomatoes, 363 
Journal of Heredity, 300 
Judging the individual, 591 
Juglans californica var. quercina, 265 
californica * nigra, 297, 364 
californica * regia, 364 
nigra X regia, 364 
K 
Keeble and Pellew, heterosis, 232 
vigor in Ff; hybrids, 326 
Keeping varieties pure, 341 
Kellerman, Miss, preserving pollen, 350 
Kent, correlation in poultry, 507 
Khang-hi, imperial rice, 287 
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