Mendelism and eugenic practice, 97, 233. Mendel's law, and unit characters, 95-99. characteristics inherited according to, 98, 99. human, 142, 143. complications of, 100. present limitations of, 100-102. Mental ability, pedigrees of, 176-181. Mental defect, heredity of, 147, 160, 165, 162-169. Mental traits, heredity of, 143-147. Models, illustrating variability and variation, 59, 63-64. Murders, number of, 30. Mutation, 63-66. National Association of British and Irish Millers, 133. Natural selection, 21-23, 45. Nettleship, pedigree of night blindness, 158-163. Night blindness, heredity of, 143. pedigrees of, 157, 158, 161, 163. Normal frequency curve, 56-60. Nurture, 17, 76. Oedema, pedigree of angio-neurotic, 168-170. Ohio Institution for the Feeble-Minded, superintendent quoted, 33. Oneida community, 10. Ontogeny, 51. Oöphorectomy (oöphorotomy), 218-222. Order of birth and pathological defect, 123-126. Oxford, mental heredity in graduates of, 146, 147. Paupers, United States census of, 34. Pearson, Karl, 14, 27, 36. heredity in school children, 143, 144. quoted, 127-130, 216-218, 225-227. Pedigrees of ability, 176-181. Pedigrees of angio-neurotic oedema, 168, 170. of brachydactylism, 150-153. of cataract, 157, 159. of deaf-mutism, 160, 167. of feeble-mindedness, 162-169. of Huntington's chorea, 160, 165. of infertility, 174, 175. of lobster claw or split hand, 155-157. of night blindness, 157-163. of polydactylism, 155, 156. of tuberculosis, 168-171. Plato, 3, 9. Ploetz, Dr. Alfred, 230. Poellman, family described by, 181. Polydactylism, heredity of, 142. pedigree of, 155, 156. Population, of Europe and North America, 25, 26. Practice of Eugenics, 192-240. Prisoners, number of, in United States, 29, 30. Probability, law of, 56-59. Pure bred, 97. Pure line, 67, 72. Recessive characteristics, 85. Regression, 105-108. Regression line, 106, 107. Rentoul, statistics of defectives, 31. Rentoul's operation, 218-222. Research, in the eugenic program, and need for, 196-215. Restrictions in marriage, 154, 155, 230, 231. Royal Society, mental heredity in Fellows of, 145, 146. School children, heredity in, 143, 144. Schuster, on mental heredity, 146, 147. Scottish Commission, statistics of insane, 31. Selective fertility, 113-122. Sex limited heredity, 100. Size of family, 114, 115. and relative proportion of defectives, 126. Social practices, investigation of, 207-212. opposed to Eugenics, 227, 228. Social status, and birth rate, 116-123. Social variation, 75. Society for social and racial hygiene (Munich), 230. Sociological Society, 12. Sociology, aims of, 35, 42. and Biology, 8, 35-45. Span, heredity of, 140. Species, relation of, to pure line, 66. Split hand. _See_ Lobster claw.