External conditions, effects of, 199-203. Eye color, heredity of, 140, 142, 143. Fabian Society, 122. _Familie Zero_, 184-187. Family histories. _See_ Pedigrees. Feeble-minded, in Great Britain, 32. in United States, 34. Feeble-mindedness, pedigree of, 162-169. Fellows of the Royal Society, mental heredity in, 145, 146. Fertility, and social status, 116-123. differential (selective), 113, 121. in normal and pathological stocks, 115. of various classes, 120, 121. Fluctuation, 56. Forearm, heredity in length of, 140. Fowl, color heredity in Andalusian, 81-83. Functional modification, non-inheritance of, 199-207. Galton, Sir Francis, illustrations of variability, 58, 63. in history of Eugenics, 9-13. on mental heredity, 144-146. pedigree of, 181-183. quoted, 5, 44, 45, 236, 239, 240. Gametic coupling, 100. Germ, relation of, to adult structure, 50. Germ cells, relation of, to Mendel's law, 88-94. Goddard, account of feeble-minded family, 162-169. Great Britain, number of defectives, etc., 31, 32. Greece, 9, 10. Guinea-pig, heredity of color in, 84-87. Hæmophilia, heredity of, 143. Hair color and curliness, heredity of, 140, 142. Harrow, mental heredity in students of, 147. Head measurements, heredity of, 140. Heredity, coefficient of, 109, 140. definition of, 77. human, 137-188. Mendelian formula of, 80-102. in human traits, 142. need for studies in, 212, 213. of acquired characters (modifications), 199-207. psychic characters, 143-147. relation of, to Eugenics, 78, 79. statistical formula of, 80, 102-113. Heron, David, birth rate, and net fertility of social classes, 116, 119-121. Homicides, number of, in United States, 30. Huntington's chorea, heredity of, 143. pedigree of, 160, 165. Idiots, statistics of, 32. Imbeciles, statistics of, 32. Imbecility, heredity of, 143. Immunity, relation of, to heredity of disease, 168-173. Index of variability, 62. Indiana, vasectomy statute of, 218, 219. Infection, heredity of, diseases and defects due to, 168-173. Infertility, pedigree of, 174, 175. Inheritance. _See_ Heredity. Insane, statistics of, 31-34. Insanity, and order of birth, 124-126. associated with alcoholism, 205, 206. _Internationale Gesellschaft für Rassen-Hygiene_, 230. Jennings, 66. Johannsen, 66. Jordan, David Starr, quoted, 209. Jörger, _Die Familie Zero_, 184-187. "Jukes" family, 182-184. Keratosis, heredity of, 142. Lankester, Sir E. Ray, "Kingdom of Man," 21-24. quoted, 7. _L'Elite_, 10. Lobster claw, heredity of, 155. pedigree of, 155, 157. London, number of children in, 122. university of, 14. Man's place in Nature, 6, 7. Marriage, antecedents to, 238, 239. restrictions in, 228-232. Mediocrity, 61. Mendel, Gregor, 83, 84. Mendelian formula of heredity, 80-102.