mental, 197-240;
  human faculty as a product of, 212;
  mental as real as physical, 214;
  of brain, 214-217;
  of art of writing, 223;
  method of mental, 231;
  social, 241;
  of societies of insects, 258;
  human, biological interpretation of, 267-274;
  of higher human life, 278-311;
  of ethics, 285;
  final conception of, 307-311.

Factors, primary, secondary, 110;
  three kinds, 111;
  congenital, 113.

Falls of St. Anthony, 86.

Fishes, lowest among common vertebrates, 46;
  trunk-fish, cow-fish, puff-fish, mouse-fish, flounder, 46;
  most primitive backboned animals, 92; 94; 157;
  embryos of, 171.

Fiske, 139.

Flies, may, 259.

Flounder, a variant of the fish theme, 66.

Fossilization, conditions of, 77-78.

Fossils, 73-105;
  remains of, 73;
  groups, 77; 78, 79;
  order of succession, 91;
  oldest rocks devoid of, 92;
  forms, 99.

Fowl, game cock, 138;
  pigeons, 138.

Frog, 45;
  eggs of, larva, development of, 58, 59, 60, 68.

Galapagos Islands, 102, 103, 104.

Galton, 142, 147;
  heredity of mental qualities, 232.

Gametes, 252.

Gastrula, 68.

Gemmules, 143.

Genera, 32.

Generation, spontaneous, 78.

Geographical distribution, 32.

Geological agencies, rain, rivers, glaciers, 88;
  construction, volcanoes, 88.

Geology, data of, 83, 84.

Germ, Bonnet’s idea of, 70;
  cells, 144, 146;
  plasm, 145, 146.

Gibbon, 163.

Gills, 58, 62.

Gill-slits, bars, clefts, 61, 62, 64;
  in embryos of lizards, birds, mammals, 69; 171.

Giraffe, 133.

Glaciers, alterations made by, 87.

Goats, 157.

Gorilla, 163, 165, 195.

Grand Canon of the Colorado, 85, 90.

Gravitation, 155.

Guinea-pigs, Brown-Sequard’s, 148.

Gulick, 103.

Haeckel, 63, 71, 184.

Haemoglobin, 22.

Hapalidae, 160.

Harvey, 70.

Hawaiian Islands, 103;
  snails of, 104.

Heredity, 142;
  a real human process, 175;
  instinct determined by, 206;
  Anglo-Saxon, 213;
  of mental qualities, 232.

Heron, 44.

Hesperornis, 99.

Hippopotamus, 42.

Hominidae, 160.

Homo sapiens, 183.

Hoofed animals, 95, 96, 97.

Hornets, communities of, larvae of, 260.

Horse, 41, 42, 65;
  place of in zooelogical science, 95, 96;
  development of, 97;
  perfection of one type of, 136, 157; 167;
  intelligence of, 209.

House-fly, eggs of, 67.

Human faculty, 212;
  its three constituents, 212.

Huxley, 6, 26, 30, 63, 184.