INDEX 655 
Davenport, C. B., ‘‘bleeders,” 524 
Mendelism in sheep, 476 
Ovarian regeneration, 487 
Davenport, E., corn experiments, 3 
dynamic evolution, 438 
horses, 496, 497 
prepotency, 573 
telegony, 565 
Davis, chromosome counts, 285 
(nothera, 247, 248 
investigations, 283 
seed sterility in, 283 
Deciduous tree fruits, 393 
Decreased vigor in species hybrids, 230 
Deer, antlers in the male, 214 
Deeringia celosiodes, chimeras in, 381 
Defectives, proportion of, in population, 526 
Defects in domestic animals, 526 
in man, 524 
inheritance of, 524 
“Deficiency,” 
194 
Descriptions, need of accurate, 428 
Determination of sex, 536 
Determiners, 71 
Detlefsen, agouti factor, 575 
Bos species hybrids, 520 
Cavia species, 235, 23 
Cavy hybrids, 223, 
guinea-pigs, 558 
species hybrids, 236 
Development of the individual, 3 
Dewey, purple-leaved hemp, 270 
Dianthus, hybridized, 438 
vegetative vigor in species hybrids, 230 
Dichotomy, method of, 96 
Differences between variations, 18 
in organisms, 1 
minute, heritable, 451 
Digitalis, 438 
matroclinous F) in species hybrids, 229 
purpurea * D. ochroleuca, 230 
Dihybrid ratio, 86 
modified, 89 
Dihybridism, 81 
in Drosophila, 87 
Dimorphism fixed, 48, 276 
in plants, 275 
Dicecious plants, 317 
Direction of variations, 20 
Discontinuous variations, 18 
in horticulture, 274 
Disease and animal breeding, 522 
defined, 522 
immunity to, 527 
inheritance of, 522 
Disease-resistance, nature of, 401 
of species, 401 
testing for, 416 
Disease-resistant plants, breeding, 295, 400, 413 
strains, selecting, 417 
Diversity, germinal, in populations, 317 
of ancestry in domestic animals, 460 
Dog, telegony, 565, 570 
in Drosophila ampelophila, 121, 
Domestic animals, variation in, 454 
characters of, 454 
diversity of ancestry, 460 
germ-plasm of, 459, 460 
Mendelism in, 465 
mutations in, 462 
species hybridization in, 515 
fowl, origin, 461 
plants, varieties of, 302 
Domesticated animals and plants, mutations, 
282 
Domestication and fertility, 551 
Dominance, 69 
and heterosis, 232 
defined, 144 
extent of, 144 
in round and wrinkled peas, 145 
Dominant factors and heterosis, 231 
mutations, 267, 274 
reaction system, 242 
Doncaster, aberrant sex-ratios, 208 
Abraxas, 206 
sex-differentiator, 209 
Dorsey, apple, 393 
Downing, hybridization, 294 
Drosophila, architecture of germ-plasm, 459 
chromosome number in species, 263 
mutations comparatively rare, 267 
reaction system concept, 575 
viability of mutants, 321 
Drosophila ampelophila, abnormal abdomen, 26 
allelomorphic relations in, 145, 146 
bar eye in, 149, 152 
chromosomes in, 57, 58 
different factors producing similar effects 
in, 141 
dihybridism in, 87 
dominant mutations, 267 
eye-color factors, 194, 215 
factor differences causing decreased vigor, 
233 
causing sterility, 234 
factors affecting fertility, 554 
genetic investigations in, 9, 126, 607 
giants and dwarfs in, 130 
inbreeding, effects in, 553 
inheritance of sex in, 66, 67 
lethal factors in, 132, 133 
linkage in, 110, 127, 162 
miniature wings in, 146, 170 
modifying factors for eye color, 192 
multiple allelomorphism in, 156, 161 
mutations in, 29, 154 
non-disjunction in, 198 
pigmentation in, 261 
return mutations in, 154 
segregation in, 64 
sex in, 196 
size differences, 177 
truncate-winged, 168 
white eye color in, 74, 87, 197, 208, 269 
Drosophila melanogaster = D. ampelophila, 
Duchesne, hybrids, 438 
Duchess Shorthorn cows, 556, 580 
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