Felt, making of, v, 289 Fer-de-lance, xii, 234 Ferdinand II of Tuscany, i, 69, 213 Fergusson, William, x, 130 Fermat, Pierre de, xvi, 105, 114, 119 Fermentation, alcoholic, viii, 248-9; of sewage, 328; of sugars, 225, 227; on what dependent, xiii, 66, 71; Pasteur's studies in, x, 137, 138-9, 141, 143 (see Alcoholic Fermentation) Ferments, viii, 357, 376; as catalyzers, 103 Ferns, xiii, 63-6; classification, iii, 251; cycad-like, xiii, 309; evolution, iii, 252, 254, 256, xiii, 303, 317; fossils, iii, 272 (Pl. 15), xiii, 324; in tropical forests, xiv, 368; mosses and, xiii, 69; number of species, 323; power of roots, 19; reproductive processes, 155-60 Ferrel's Law, i, 124-5 Ferrets, xii, 349 Ferric Compounds, viii, 161 Ferrite, viii, 160, 273 Ferrous Compounds, viii, 161; action of oxygen on, 194 Fertilization of Plants, xiii, 118-65; devices to insure, 48-53; of yucca plant, xvi, 152-3 (see also Cross Fertilization) Fertilizers, viii, 278-80, 342-6; ammonium, 147; garbage, 330, 343; natural, 327, 342-4; natural, in southern China, xiv, 73; nitrogen, i, 34, viii, 72, 74, 75, 137, 280, 345-6, xiv, 66; phosphate, viii, 89, 153, 279-80, 344-5, xiv, 67, 68; potassium, viii, 134, 146, 278-9, 344; potash, xiv, 67-8; primitive knowledge of, xv, 202 Festoon Clouds, i, 104, 372 Fetal Anlage, x, 120 Fetishes, xv, 348-9 Fevers, cause, temperature, and treatment, ix, 317-19; cooling of skin in, iv, 174; explanation of phenomena, x, 214; heart rate in, 334; improvement of treatment, xvi, 184-5; inanition in, x, 276; racial immunity and susceptibility to, xv, 50, 51; Sydenham's treatment of, x, 73; use of antipyretics in, 381 Fibers, cellulose, viii, 254-6; sources, uses, and kinds, xiii, 235-45 Fibrin, ix, 180 Fields, electrostatic and magnetic, vii, 368 (see Electrostatic Fields, Magnetic Fields) Field Strength or Intensity, vii, 368, 370 Figs, for constipation, ix, 251; origin, xiii, 225 Fig Trees, antiquity of species, xiii, 324-5; of Bahamas, 18; of Brazil, 365; of India (illus.), 16; of West Indies, 21 Filled Space, xi, 187 Filled Time, xi, 194 Filterable Viruses, x, 200 Final Common Path, xi, 22-3; in acquired tastes, 73; in association of ideas, 199; in attention, 230; preoccupation of, 119, 120, 121 Finches, coloring of, xii, 245-6 Fingal's Cave, jointed rocks in, xiv, 129 Fingers, bones of, ix, 67, 68, (fig.); curling of, in infants, ix, 349; flexed position, xi, 42-3; muscles for operating, ix, 76; of men and apes, xv, 60 Finland, coast of, xiv, 247, 259; lakes of, 200 Finland, Gulf of, salinity, xiv, 296 Fiords, (see Fjords)