164 The Third and Fourth Geneeation 



Phenotype, gi 



Pigeons, origin of domestic, 48 



Pistil, 19 



Pollen, 22 



Polydactylism, 124 



Potato-beetle, 113 



Potato, Burbank's, 54 



Poultry, selection for egg pro- 

 duction, 64 



Prenatal influence, 81 



Prepotency, 64 



Primrose, evening and mutants, 

 52 



Protoplasm, 67 



Pure line in breeding, 38, 59 



Rabbits, factors in coat color, 89 

 Racial improvement, 151 

 Rebekah and Isaac, 146 

 Recessive, 36, 42 



Reduction of chromosomes, 74, 84 

 Reproduction, 28; value of sexual, 



83 

 Reversion, 87 

 Romanhoffs, family pedigree, 137 



Saltation, 53 



Seed, 24 



Segregation of characters, 40, 78 



Sex chromosome, 78, 79 



Sex determination in man, 79 



Sex-determiner, 79 



Sexes, equality in numbers, 80 



Sex-linked characters, 97, 98, 150 



Sex-linked inheritance, 97 



Sexual impurity, diseases of, 119, 



150 

 Sexual reproduction, value of, 83 

 Sheep, Ancons, 49 

 Sins of the fathers, 120, 121 



Social inheritance, 112, 113 



Somatoplasm, 107, no 



Sperm, 25, 28, 67, 72 



"Sports," 52, 64 



Stamens, ig 



SteriUzation of the undesirables, 



120 

 Syphilis, 118, 150 



Tadpole, 27 

 "Tail-male" descent, 7 

 Trotted mile, time of, 4 

 Trotters, American, 5 

 Tuberculosis, inheritance of, in 

 Turkey under domestication, 48 

 Tuttle, Mary, 15 

 Twins, identical, 83 

 Types, improved, 59 



Uhlan, champion trotter, 5 

 Undesirables, propagation of, 152, 



154 

 Unit character, 88 

 Uterus, 66 



Variation, 83 



Venereal diseases, 118, 119, 120, 



150 

 de Vries, Hugo, 53 



Wedgewood, Josiah, 10 

 Weismann, theory of continuity 



of germ plasm, 107 

 Wheat, 56, 58, 93 

 White rats, experiments with 



alcoholized, 116 

 Womb, 66 



JT-chromosome or sex chromo- 

 some, 78 



