664 
Mendelism in domestic animals, 465 
mathematical adequacy of, 77 
operation of, 68 
physical basis of, 57 
principle discovered by Naudin, 439 
rapid development of, 71 
Mendelizing characters, due to factor mutations, 
286 
in domestic fowls, 477 
Mercer and Hall, experimental error, 430 
Meristic variations, 16 
Mespilus-Crategus graft-hybrids, 378 
germanica, 378 
Metabolic theories of sex, 544 
Method of comparing yields, 356 
of cytology in genetic research, 8 
of experimental breeding, 6 
morphology, 10 
of hybridization, general, 343 
of observation in genetic research, 4 
of producing hybrid seed corn, 361 
Methods of breeding animals, 577 
of breeding investigations, 591 
of creating new varieties of plants, 302 
of dealing with genetic data, 95 
of pedigree culture, 419 
of planting, 420 
of protection, 420 
of recording and preserving data, 422 
of seedage, 419 
of testing Mendelian ratios, 100 
Metz, Drosophila, 263 
Meyer, seed and plant introduction, 299 
Meyer and Schmidt, stock and scion, 384 
Mice, affected by temperature changes, 491 
disease in, 527, 529 
effects of alcohol on, 493 
four-fold factor segregation in, 94 
multiple allelomorphs in, 155, 160, 225 
Miles, factor variability, 134 
Milk, efficiency, 503 
production records, 445, 455, 591 
Milo, resistant to smut, 416 
Milward, certified seed, 397 
Miniature wings in Drosophila, 146, 170 
Minot, sex-ratio, 542, 543 
Mirabilis jalapa, intermediate 
heterozygotes, 147 
vigor in species hybrids, 230 
Mitosis, 59 
and somatic segregation, 274 
expression in 
mechanism of, 274 
Mixed populations, isolation of pure lines, 256 
Mode defined, 34 
Modifiability and breeding value, 456 
and correlation, 459 
and selection, 578 
and variation, 454 
in fecundity, 498 
Modification of graft-symbionts, 383 
Modifications, 15 
functional, inherited? 481, 489, 491 
not transmissible, 385 
of phytomeres, 385 
INDEX 
Modifying factors, assumed in hooded rats, 190 
discovered in Drosophila, 192 
Moenkhaus, Drosophila, fertility, 553 
Mohler, zebu immunity, 528 
Molecular configuration and specificity, 266 
Mongrel dairy cows, 455 
ponies, 567 
Moneecious plants, 317 
Monohybrid, 68 
ratio, 71 
van Mons, plant breeding, 437 
systematic breeding, 288 
Montgomery, E. G., experimental error, 430, 431 
wheat, 432, 433, 434 
Montgomery, T. H., chromosomes in man, 538 
Morgan, abnormal abdomen in Drosophila, 26, 
134 
crossing-over, unit of, 117 
dominant mutant factor, 149 
effects of ether on Drosophila, 74 
eye color in Drosophila, 194 
factor group, determination, 115 
relations, 575 
factors, lethal, 132 
manifold effects of, 133, 134 
similar effect of, 141 
gynondromorphism, 269 
heredity, factor conception of, 110 
hickory phylloxeran, 211 
lethal factor, 547 
linkage, 110, 116 
Mendelism, 68 
multiple allelomorphism, 155, 160 
presence and absence hypothesis, 155 
sex-ratio, 540 
sterility, 554 
three-point experiment, 118 
white eyes in Drosophila, 74 
WZ type of sex-inheritance, 205 
XY type of sex-inheritance, 196 
Morgan and Bridges, crossing-over, 113 
data, three-point experiment, 118 
Drosophila mutation, 555 
three-point experiment, 123 
Morphological variations, 16, 17 
Morrow and Gardener, increased yield from 
hybrids, 354 
Morse, sweet pea, 208 
Morton, quagga hybrid, 565 
Mosaic expression of the hybrid character, 
152 
Mosquito, yellow fever, 528 
Moths, grafted, 382 
intersexes in, 216, 217 
sex-inheritance in, 205, 209 
Mule, breeding industry, 516 
chromosomes in, 559 
Equus caballus X E. asinus, 228 
fertility of, 518 
reduction divisions in, 558 
sterility of, 556 
Mullein thrips, see Anthotrips verbasci. 
Muller, crossing-over, double, 124 
factors for, 120 
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