668 



INDEX 



Pigmentation, extent of, affected by modifying 

 factors, 190 



in Droeophila and Leptinotarsa, 261 



modification of, in Coleus, 380 

 Pine, Ft hybrids in, 365 

 Pineapple, heteroaia in, 364 

 Piper, alfalfa, 296 



environment factors, 433 



Florida velvet bean, 367 



variety testing, 435 

 1 'i.-uin sativum, 80 



linkage in, 125 



Plane, London, an Fi hybrid, 365 

 Plant breeding, beginning of, 287 

 material, 299 

 methods, 419 



classified, 291 

 organization of, 299 

 pioneers in, 288, 437 

 progress, 291 

 relation of science to, 437 

 to genetics, 440 



breeders, organization of, 300, 301 



disease, 400 



groups, research on, 300 



improvement, earliest, 287 



introduction, 299 



populations, composition of, 317 



-to-row method, 337, 433 

 Planting, methods of, 420 

 Plants, crop, 288, 289, 302 



cross-fertilized, 317 



inheritance of sex, 212 



monoecious and dioecious, 317 



reproduction in, 317 



self-fertilized, 317 



varieties in, 302 

 Plough, crossing-over, temperature effect on, 120, 



121 



Plumcot, 297 

 Plums, aphis-resistant, 297 



breeding, 297 



collections, 299 



hybridization, 311 

 Pollen, grains of hybrids non-functional, 237 



preservation of, 350 



protection of, 343 



transportation, 300 



viability, 300 

 Pollination, artificial, 343 



natural methods of, 317 

 Polygamous plants, 318 



Polyphyletic origin of domestic animals, 460 

 Pomace fly, see Drosophila ampelophila. 

 Pomology, importance of bud selection, 391 

 Poplar, Black Italian, an Fi hybrid, 365 

 Poppy chimeras, 381 

 Population, 37 



containing biotypes, 260 



nature of variations in, 317 

 Populations, as affected by crossing, 321 



composition of plant, 317 



creating at Svalof, 352 



normally self-fertilized, 320 



Populus, canadensis-trichocarpa, graft-hybrids, 

 378 



Fi hybrids in, 365 



generoea, a vigorous hybrid, 365 

 Potato, at Svalof, 293 



bud selection, 394 



certified seed, 397 



clonal selection, 298 



graftage of, 374 



heterosis in, 364 



ideal market tuber, 397 



Magnum Bonum, 290 



mutations in, 369 



running out or degeneration, 395 



sudden degeneration of, 397 



tuber-unit method, 395 

 Potency of sex-factors, 217 

 Poultry, see Fowls, ducks, etc. 

 Powell, apple, 393 

 Practical breeding, service of genetics to, 449 



importance of pure varieties, 341 



value of crossing corn, 361 

 Predisposition to disease, inheritance of, 523 

 Prepotency, fact of, 573 



factor potency interpretation, 575 



greater in male, 576 



hereditary complex interpretation, 575 



Mendelian interpretation, 574 



recognized, 501 



Presence and absence hypothesis, 153 

 Primary non-disjunction, 199 

 Primula, hybridization by Dutch, 287 



kcwensis, chromosomes, 264 



sinensis rubra, 26, 134: 

 Primrose, Evening, see CEnothera. 



linkage in Chinese, 125 



Principles of composition of populations, 324 

 Pringle, hybridization, 292 



wheat rust, 411 

 Pritchard, experimental error, 430 



sugar beet, 340, 369 

 Probable error, 45 



experimental determination of, 430 



of a difference, 47 



significance of, 47 

 Problems of animal breeding, 447 



of genetics, 4 

 Progeny test, 291, 293 

 Progress in plant breeding, 291 

 Progression method of computing Ft genotypes, 



97 



Progressive mutations in Boston fern, 315 

 Promiscuous crossing, results of, 343 

 Propagation of mutations, 372 

 Protection, of cultures, methods of, 420, 421 



of developing seed, 344 



of pollen in hybridization, 343 



of pollinated flowers, 344 



special devices, 344 

 Proteins, specificity of, 266 

 Protoplasm, problem of nature of, 268 

 Protoplasmic constituents, molecular structure, 



266 

 Primus, research on, 300 



