Apes, anthropoid, xii, 381-4; black of Celebes, 379; brain of, xv, 62, 90-1; embryological development, 54-5; imitation in, 66; manlike, iii, 301-3, xv, 88-95; man's relation to, xv, 56-7; nostrils of, xii, 376, xv, 46; physical comparison of, with man, iii, 301, (fig.), xv, 57-62; reasoning power, 67-8; sex relations among, 277-8; skull capacity, xv, 89; skull shape, 42-3; tigers and, xii, 362; tool-using by, v, 9; working methods, xv, 58 Aphids, xii, 118; ants and, 101 Aphis Lions, xii, 106 Aphrodite (sea mouse), xii, 54 Apian, Peter, ii, 41; comet of, 85 Aplysia, xii, 68 Apollonius of Perga, ii, 31, xvi, 90 Appalachia, iii, 195, 205, 210 Appalachian Mountains, antiquity of, xiv, 96, 235; Catskill formation, iii, 195; coal beds, iii, 346-7, 204, xiv, 237; folding intensity, iii, 86, xiv, 36, 230; forests, xiv, 372; former elk of, xii, 317; geological history, iii, 130, 132-4, 135-6, 140, 191, 205-7, 210, 219, xiv, 97-8, 168-9, 228-9, 235-6; "grain" of, xiv, 99; historical rôle, 191, 194, 242-3, 249; igneous formations absent, 228, 230, 234; iron deposits, iii, 358-9; length and breadth, xiv, 36-7, 227; limestone soils, iii, 27; marble production, 371; metallic ores of, xiv, 237; non-marine deposits in trough, iii, 209-10, 214; petroleum fields, 350; plateau west of, xiv, 221; present relief, origin, iii, 231-2; ridges and valleys, 36, 137, 233-4, xiv, 94, 97-8, 234, 236; rivers across, iii, 36, 137, 233, xiv, 166-7, 168-9, 180-2; site formerly submerged, iii, 12, 130, 168, 181, 184, 187, 194-5, 197, 198; springs, thermal and mineral, 128, xiv, 143; strata, thickness and composition, iii, 132, 180, xiv, 228-9; strata of various periods, iii, 184, 187, 195-6, 203; stream capture in, xiv, 180-2; thrust faults, iii, 90; typical range, xiv, 226; wind and water gaps, iii, 39, xiv, 58, 98, 169 Appalachian Revolution, iii, 205, 208, 210 Appalachian System, xiv, 227 Appalachian Valley, xiv, 167 Appendicitis, asepsis in, x, 147; cause of, 224 Appendix, ix, 233 (fig.); as infection center, x, 220; in man and animals, xv, 56 Appetite, ix, 87-8, 299; exercise effects, x, 303-4 Apples, acids of, viii, 223; development of, xiii, 54; food value, viii, 365, ix, 250-1, 299, x, 268 Apple Tree, family, xiii, 197-8; origin, 224; petal arrangement, 190 Apteryx, xii, 249 Aquamarine, iii, 325 Aqua Regia, viii, 174 Aquatic Animals, mental inertness of, xii, 140, (see also Crustaceans, Mollusks, Naids, Polyps) Aquatic Plants, first on earth, xiii, 300, 301, 303; fertilization, 123, 149-52; fossils, 303; in lakes, xiv, 210