INDEX 



723 



Parthenogenesis, 162 ; but one polar 

 body in, 179; influenced by condi- 

 tions of life, 178 ; influenced by tem- 

 perature, 281 ; Loeb's experiments in, 

 278-282 ; but half the normal num- 

 ber of chromosomes in, 180. 



Parthenogenesis and mutation, 179. 



Parthenogenetic reproduction, variation 

 in, 177-180. 



Particulate inheritance, 476. 



Paulmier on the accessory chromosome, 



635- 



Pearson, on bathmic influences, 203 ; 

 on causes of variability, 220; on fer- 

 tility, 196-198 ; on law of ancestral 

 heredity, 529 ; on reduction of varia- 

 bility, 536; on telegony, 188. 



Pedigree, importance of, 592 ; records 

 of, 670-672. 



Pedigrees, fashionable, 595. 



Peloric flowers in toadflax, 115-118. 



Performance, as a guide to breeding 

 powers, 558-567 ; records in plant 

 breeding, 650. 



Pfeffer, experiments on chemotropism, 



273- 



Photosynthesis, 240. 



Phototaxis, 248. 



Phototonus, 248. 



Physiological selection, 201, 589. 



Physiological units, 14, 17, 152, 208- 

 213 ; as affected by reduction, 170. 



Pigs, acclimatization of, 375; develop- 

 ment of, 58 ; meristic variation in 

 digits of, 63. 



Planarian, regeneration of, 321, 322, 

 334, 335 ; regeneration of starving, 

 327 ; regeneration of, when split, 335. 



Plant breeding, 639-651; advantages 

 and limitations of, 639-641 ; plot or 

 row system for, 644-649 ; soil and 

 culture conditions for, 641-643; sys- 

 tems of planting in, 643649. 



Plant lice, effect of conditions upon 

 reproduction, 102; parthenogenetic 

 only at high temperatures, 281. 



Plants, effect of heat upon growth of, 

 255-257 ; regeneration in, 325. 



Plot system of planting in breeding 

 work, 644-646. 



Plums, evolution of, 133. 



Poison ivy, immunity to, 308. 



Poisons, acclimatization to, 308-311, 

 381, 382; catalytic, 266, 267; from 

 insects, 270 ; toxic, 268. 



Polar bodies, 164; formation of, 167; for- 

 mation of, illustrated,! 68 ; fertilization 

 by, 179, 1 80; formation of second, 167. 



Polarity, in struggle with gravity, 237 ; 

 of ovum, 341-343. 



Pollination, indirect effect of, 185. 



Polymorphism in practical breeding, 

 476, 477 ; with regard to sex, 20. 



Pork, effect of cotton seed upon, 

 228. 



Precipitin test, 382. 



Preferential mating, 163. 



Prenatal influences, 189-191. 



Prepotency, 551, 575; as affected by 

 a g e 573 as indicated by perform- 

 ance, 558-567 ; as related to consti- 

 tutional vigor, 573 ; as shown by 

 trotting records, 551-566; influence 

 of development upon, 574 ; because 

 of sex, 567-570. 



Primrose, seven mutants in eight gen- 

 erations of, 127. 



Probability, 692-698 ; combination of, 

 693, 694 ; definition of, 693 ; place of, 

 in science generally, 692, 693. 



Probability curves, 695-701 ; normal 

 curve, 696, 699, 701. 



Probable error, 437-440, 698-703; of 

 coefficient of correlation, 459-468, 

 703, 711 ; of coefficient of variability, 

 441.703,710; of coefficient of regres- 

 sion, 466, 703 ; of mean, 440, 701, 703; 

 of single variate, 698, 703 ; of stand- 

 ard deviation, 440, 702, 703. 



Probable error and deviation illustrated, 



441-443- 



Probable error in estimate of probabil- 

 ity, 709-713. 



Progression, a few offspring extreme, 

 492-498 ; in oil content, 496-498 ; in 

 protein content, 493-495 ; origin of 

 the exceptional individual, 499, 500. 



Protein content of corn, 83-85 ; effect 

 of selection upon, 445, 446; progres- 

 sion in breeding for, 494, 495. 



Protoplasm, a chemical substance with 

 chemical properties, 144; activity of, 

 due to external as well as to inter- 

 nal impulses, 398-401 ; as influenced 

 by chemical agents, 264-285 ; effect 

 of contact upon, 233-236; effect of 

 gravity upon, 239 ; effect of heat and 

 cold upon, 255; irritability of, 398; 

 effect of external agents upon, 396, 

 397; physical basis of life, 142, 143; 

 relative stability and mutability of, 



295' 346. 

 Protozoa, but one maturation division 



in, 165. 

 Python, meristic variation in vertebrae 



and ribs of, 39, 40. 



